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Un dee symboles solvents apparaitra sur la darnlAre image do cheque microfiche, salon la cas: la symbols -^ signifie "A SUIVRE", le symbols V signifie "FIN". IMeps, pistes, chsrts, stc, may be filmed et different reduction ratios. Those too large to be entirely included in one exposure ere filmed beginning in the upper left hand corner, left to right and top to bottom, as many frames as required. The following diagrams illuatrata the method: Les cartes, planches, tableaux, etc., peuvent Atre filmAs A des tsux do rAduction diff Arsnts. Lorsque le document est trop grand pour Atra raproduit en un soul ciichA, il est fiimA A pertir do i'sngie supArieur gauche, do gauche A droite, et do haut an baa, an prenant la nombre d'imagas nAcssseire. Les diagrammas suivants iilustrant la mAthoda. 1 2 3 3» 1 2 3 4 5 6 %'"''M \s ^»> j '•^''^•'y^Z'/'^^^}^'*: ..-T.-s McGILL UNIVERSITY PAPERS FROM THE DEPARTMENT or Geology. No. 5. — Geology of a Portion of the Laurentian Area TO THE North of Montreal. BY Frank D. Adams. [Rq>rinted from the Geological Survey of Canada, Vol. viii., Ft. J.] »»% Montreal, 1897. ^( -^_, »ii ti^ ^. « '- m i II I i - (I- X * ^ . Tv t , «^ ," .,->«; ^■', ' ' *; '''A w o CO X »5 !/3 K w B O cn Nit : ?' *i 'V (' ^, i ! 1 :' F [ f I BHPIiPWW3BBW!?!?w i ,- Mi GEOLOGICAL SURVEY OF CANADA G. M. DAWSON, C.M.G., LL.D., F.R.8., Director REPORT ON TlIK GEOLOGY OF A PORTION OF THE yURENTlAN AREA LYIS<; Til TIIK NORTH OF THE ISLAM) OF MWIUI BY FRANK D. ADAMS, Ph.D., F.G.S., F.R.S.C. ? '1 f": J !] Ill ;'' ' ', ;i ^1- t ^'4 |;i I M OTTAWA PRINTED BY 8. E. DAWSON, PRINTER TO THE QUEEN'S MOST EXCELLENT MAJESTY 1896 in To George M. Dawson, C.M.G.. LL.D., F.R.S., Director of the Geological Survey of Canada. SiH, — I beg herewith to submit to you a Keport upon the Geology and Economic Resources of that portion of the Laurentian region lying to the north of the Island of Montreal, together with a geologi- cal map of the same. In the spring of 1885 I was instructed by Dr. A. H. C. Hclwyn, then Director of the Survey, to undertake a detailed geological examination of this district, with a view to ascertaining the true character and relations of the great masses of anorthosite which occur in it and which had been supposed by Sir William Logan to constitute an upper nieml)or of the fjaurentian system. These rocks, which are also very ext -nsively developed in several other parts of the Lauren- tian, had attracted much attention on account of the large deposits of iron ore which they contain, but their true relation it was believed could best be ascertained in this distiict, which is for the most part coini)arativcly easy of access, while foi'ming as it does an eastward continuation of the Grenville district, previously mapped by Sir William Logan, it also promised to afford important additions to our knowledge of the Laurentian system as a whole. These- expectations have, it is hoped, been in a measure realized. The field work was carried out during portions of the summers of 1885, 1887, 1888 an, I 1889, and was completed in 1891 after the severance of my connection with the (Jeological Survey, to accept the Logan Professorship of Geology in Mc(}ill University. The south-western corner of the area I have not studied, as no anorthosites occur there, and that portion of tlie sheet was carefully examined by Logan, being embraced in his map of the Grenville district, which appears in the Atlas accompanying the " Geology of Canada," and published in 1865. It has also quite recently been re- ( x.imined l)y Dr. Ells, to whom T am indebted for information con- cerning the distribution of the crystalline limestones in this portion of the area. The north west and south-west sheets of the "Eastern Townships" map, issued by the Geological Survey, and the Sectional Map of the Province of Quebec, published in 1894 by the Crown Lands Depart- ment of the province, have been taken as a basis for the topography of the accompinyihg map. It has, however, been corrected and m 1 1, ,:i ■■?-. \:\V , I ' 1;' I ■ 1 I'l .1 .- ,j.. :.,r , ::1; ■'f: 4 J yUEHKr. supplemented by the more recent government surveys, as well as by extensive surveys of my own. The issue «)f ii separate map to accom- pany the present report, is necessitated by the fact that the area described is unfortunately situated at the meeting of four sheets of the g».ological map of the Province of Quel)ec, now in course of pre- paration, two of which sheets cannot Im completed for publication for some years yet. The petrographical work in connection with the Report has been carried out in part at the University of Heidelberg and in part in the petrographical laboratory of .Mc(Jill University. Previous to the conmienceinent of my survey, a certain amount of work had been done in this district, by various niemliers of the Geological Survey, at different times. Siiort visits to certain parts of it had been made by Sir William Logan, Dr. Sterry Hunt and Mr. John Lowe, a number of localities l)eing referred to liy them in the early reports of the Survey. In the summer of ISHO, Mr. 11. (J. McConnell mapped iin area of considerable si/e lying to the southern portion of the counties of Bertliier, Maskinonge and St. Maurice, a small portion of which is included in the present map. Mr. H. (J. Vennorand Mr. Lewis R. Ord also examined portions of the district iit 187'.>-fSO. A short statement concerning the wt)rk of these three gentlemen is contained in the Summary Report of the Operations of the (Jeological Corps, by Dr. A. R. C. Selwyn, lH7!)-80, pp. .-{.n. My warmest thanVs are due to Prof. Rosenbusch of Heidt-lberg for aid and advice on many points connected with the pt'trography of this district ; also to Prof. Carlyle, formerly of MctJill University, now Provincial Mineralogist for Rritish Columbia, who ably assisted me during the seasons of 1885 and 1887, as well as to Mr. Walter C. Adams, R.A.Sc, Mr. Nevil Norton Kvans, M.A.Sc, and Dr. J{. J. Harrington, for chemical analyses of rocks, and to Mr. (}. H. Garden, C.E., and several other gentlemen who iiave assisted me in various ways. I have the honour to be, sir. Your obedient servant, FRANK D. ADAMS. Montreal, 25th June, 1896. 'Mem ''v^i^i^Ti-r*ftJMF^7i^i''fsSaKK- U ii u a i'!i* ii^' 'PABLE OF COXTENTS. ,■■1' ;• PAdK. I'hiiiiic'il Fnitiirif . 7 Arehtriin i/rnli){//i iiMwra] Stati'iiuMit 10 Thr LitiirrntitiH Uncimun itnil thiir Aimnfiiilnl RitrKu 11 StratiKvaphicitl Kcliitiinis 11 (irciivillc Scrii'H 11 Kull(llllllt>lltlll ( rllciMM 28 Acid IntruHiniiM 21t l'<'ti<>Krii|iliy 31 ♦ iiifiHHfH of l^tiu'ciiis Origin IW (iiit'isscs, liiiiicstoiic.i, l^iiartzitt'H, kv., of Aqufcuis <)ri(?ii) 4!t (Jui'issi'H, iVc, of ]>()ul)tful Origin 0" Th( A nitrlhimitin 85 Tilt' .Murin .\iiortiiiwitf ^y Strntigru|ilii(.'iil HrlationH . . . 8.') I'ctrogriiph.v anil iStructnn' !»1 Otlit-r A?i(irtlic>sit<' MaHStjH ll(i Laki'Kt'ld Area 117 St. .li'-roMic .Vrua 1 18 Kil(lar<' .VrraM.. 122 Cathoart Arran 1' I'ont (li'H Dall.'H Area 124 St. .It-an lit- Matlia Ari'a. 125 Brandon .\rca« 12t! Niitm nn tin AiiDrtliiitiiti n orcnrriiiij in other /niita of Ciiniidn (intt in Forritin Coiintrux 131 Piift-Archiiiin Ditkin . 134 Eeoiwntie liniloiiii 13!) Siimmiir/i of Ardidan (lioloijii IS-") Appeiiiiix I. —Litirutori' nliiliiii) to tin Anortliofitm of Ciinadii 15" ApiHnili.r II. Till' Siiiiltitiii of Titiivifiroim Ivmi On h Kil 'i Ii n- i ^% f ' in l-i Note. — The bearings given in thix reporl o,re all rejerved to the true vneridian. . REPORT ON THE CEOLOGY OF A PORTION OF THE LAlJRENTIAN AREA l,YINec. *This ( r)31 (( 555 (( 641 it 911 >< 1031 t( 1014 (1 1243 t( 1406 (( 1261 .1 711 (( 750 (t 757 (( 728 a 2380 if 274 (( 367 a Bank of River Ouireau, 300 feet above the bridge — McLaren's M ills, Grande Ligne . Ahcii.ean Geolo<:y. 2Gf; (leneral Htatfirient. r.ENKKAL STATEMENT. That portion of the area occupied by the Archa-an, is underlain for the most part by a series of gneisses, pre.senting great variations in lx)tli structure and composition, and with which are associated crystalline limestones, quartzites, itc. These belong to the Grenrilh' Series of Sir William Ixjgan,* and are of Laurentian age. In certain parts of the area, however, tl-.ere are great stretches of orthoclasc-gnciss much more uniform in character and without limestones and quart/ites. These are referable, in s'une cases at least, to the Fundamental Gneiss of Fx^gan, which was by him believed to underlie the (irenvillo series and to form the basid member of the Laurentian system. 'Geology of Canadii, 1863, p, 839. •DAMI. 1 ARCII.CAN (iEOLOOY — QENKKAL STATEMENT. 11 a Breaking through these gneisses and in some cases interbanded or inter»tratitied with tliein, are several anorthosite masses, by far the largest of these being that which for purposes of convenience may be termed the Morin anorthosite, and which comprises an area of 990 square miles. Two important intrusions of acid rocks, one of granite and the other of syenite also occur in the district. In the presi nt report the anorthnsites are shown to be intrusions, and are separatee! from the Laurentian proper. The name Laurentian is therefore made to embrace the Fundamental Gneiss, which, although, so far as can be ascertained at present, essentially igneous in origin, may possibly contain some sedimentary material, and the Grenviile Series, which is composed of altered sediments associated with much injected igneous matter. The Laukentian Gneisses and theik Associated Rocks. stkatkjrafhical relations. (irenville Series. The rocks composing the I.iaurentian in this portion of the Protaxis, usually possess a more or less distinct arrangement in the form of bands, layers or lieds which alternate with one another. That a purely objective attitude may be preserved the term band rather than bed will be employed, the latter term being usually associated with the idea of a sedimentary origin which in the present case should not thus be taken for granted. This banding is frequently replaced by a foliation caused by the liaiulinRofthc parallel arrangement of the individual grains of the several constituents "^ "' of the rock, without any distinct arrangement of these latter in bands. In any district where banding and foliation occur together they usually coincide in direction, and are often found in the same rock. In the eastern portion of the area, in the townships of Joliette, Brandon, Peterborough and Chapleau, as well as in the country to the north of these townships, these Laurentian rocks lie Hat or nearly so. Further west, as shown in the sections accompanying the map, a series of low undulations appear, while in the western portion of the area they are thrown into a series of sharp folds with nearly vertical dips, the strike varying in different places from north-east to north-west. The eastern area of flat-lying gneisses, with occasional intercalated ,,, , . bands of crystalline limestone and quartzite, extends far beyond the KneiHHCN. limits of the map to the north-east, occupying in this direction a very lai'ge district traversed by the River Mattawin, the Riviere du Loup ■\- ! . i 1 :i '■'. I. :.';U nin i !. :.' m HI I 1: QUEBEC. and other smaller streams, which cut their way down these nearly horizontal rocks, and alon^ whose banks, from time to time, as well as in the cliffs bordering; many of the little lakes drained by these streams, ;;ood sections, often representing^ a vertical thickness of from two to three hundred feet, are obtained. On the more level surface of the country on the other hand, the rocks exposed are of course compara- tively uniform in character. Over this tract of country, embracing an urea of at least 750 square miles, the gneisses often lie quite Hat, while low dips seldom exceeding 30" everywhere prevail. In several localities the direction of dip varies rapidly from place to place, low undulations in the flat gneisses being observed, running now in one direction and now in another. The whole area gives the impression of a comparatively thin crust, which has rested upon or has been sus- tained by an underlying molten or fluid mass. Granite batholite. Figure 1.— Horizontal (iniiss, ntar Ciflar Rapids, River Mattawin, (/np. That this in all probability was really the case, is shown by the appearance from under the gneisse-s, in the southern part of this dis- trict, of a great area of granite, a portion of which is seen in the north-east comer of the map. This would seem to represent a very extensive batholitic mass of granite underlying the district in question at no very great depth beneath the surface, and here partially exposed by erosion. vn these nearly time, as well as y these streams, of from two to surface of the course cojnpara- try, embracing I lie quite Hat, ail. In several ace to place, low nf? now in one the impression >r has Ijeen sus- 1, (^le. is shown by the part of this dis- ;h is seen in the I rei)resent a very listrict in question : partially exposed 4, it It CQ o •n < < ■z s w « 6S " as " a -J o ^ '] 8TI(AT|(iRAi>IIII'Ar. RKLATIONH. 13 J 92 X ■ < < - a s < a^ a H >• -/. S! S ^ :^ pi ' era: o - f" '* < < - a MS! O s a < 1-1 Kigure I. leprescntH n sketch, showing a cliff of these nearly hori/.ontiil gnt>isscH just )i€*litw the Cedar Hitpids, on the Kivor Mattiiwin, altout 20 miles beyond the northern limit of the accompanying map. Plate Iir. is a photograph ofai other clifT, consisting in this case of white garnetiforous <|uart/.itt>, interbanded with garnetiferous silli inanite gnei ses, witiiin the limits of the map, about 2 miles north- west of 8t. Jean de Mutha. « In the area embraced by the map, limestones have not been found in the Laurentian to the east of Ste. Kmilie or 8to. Beatrix, but in the tixtension of tliis district to tiie north beyond the limits of the map, Imnds of crj'stalline limestone have been found at a number of widely separated points in tin- tiat lying gneisses along the Hiver Mattawin ami about the iiciid-waters of the lliviere du Loup. At one locality t' rec miles north-west of the Lacroix Rapids, on tln^ Mattawin Hiver, reddish and grayish gneisses with interstratified <|uartzites occur in horizontal layers, with l)ands of wliite crystalline limestone, in some places (piite pure ami elsewhere holding grains of serpentine and scales iif mica. At one place, in a cliff by the side of a lake, several limestone blinds were observed, one above tlie other in the same exposure. Three Crystalliiif of these had thicknesses of three, four and eight feet, respectively. .\t anothei' point half a mile distant, two bands of limestone were seen in a similar ex| osure, the upper l)eing six feet thick, while the lower was exposed for a thickness of twenty feet, the lower limit not being seen. These bands ccld be traced horizontally in the face of the cliflP for a distance of halt a mile. Hetween Ste. Emilie, Ste. Beatrix and Radstock on the enst and the Morin anorthosite on the west, the Laurentian is thrown into a series of folds, which toward tin; .south are overturned, and in this district crystalline limestone is exposed at a number of points. Most of the exposures, however, seem to be parts of a single band repeatedly brought up by the folding, and coinciding in strikewith the surrounding gneiss. (See the sections accompanying the maj)). Some large bands of anorthosite also occur in this district. Toward its southern limit along the edge of the Paheozoic, in the townships of Rawdon and Kildare, the gneiss strikes nearly north-and-south, but going noi-th along the eastern limit of the Morin anorthosite, the strike gradually turns more and more to the west ; the gneiss wrapping itself around the anortho- site mass, until at Lac des lies it strikes N. 75° W. In the great block of gneiss which extends into the anorthosite from the north, and in which lie the valleys of Lake Archambault, Lake Ouareau and a number of smaller sheets of water, a similar coincidence .Strike of gneisH conforms to anorthosite boundary. ;i ■f- 'n 11 .1 qUKIIKC. i I I I:! |)<'t»Tiiiiii<'H I'liiirMc (if Ntrt^aiiiN. Foliiitioii ii.iliiccd by pri'ssiirf. l)«twecii the strike of the giieiHH nnd i\w direction of tlie iinorthosite lioundery it* observed. North-east of I^iike Croche iinil on the north- euHt arm of I^ake Ouareau the Htrike averages about N. 20 E., while on the west side of I^ike ( )iiareau north of Ht. Dunat and about Lake Difronay, which iH situated alx>ut the middle of the township of Lussier, it averages aliout N. 65' VV. This strike to the east of north is confined to the immediate west<^rly margin of the anorthosite, as on the north-west of l^ake Croche it has alreaily veered amund to tiie west again. The influence of the strike tif the gneiss on the shape and position of the lakes and on the course of the stroiniH is also very marke gneiHS continues ,, being N. '20 K. intftft, and N. 5 the river, further ,8 is more masive, I^ac Gauthier, on E., still following « Augmentation of terly strike, which, mass, veers around in tjuestion. B, which is at first lie latter place is ■dgeof gneiss strik- 3 for a distance of ppears beneath the iss, as will be ex- ■0 in the anorthosite ly a coarse-grained to the limits of the Sauveur, where the 23 of the Grenville series, the strike of the foliation being continuous across the boundary from the gneiss into the anorthosite. It thus becomes evident that, with the one exception just mentioned, the foliation of the gneiss runs around the anorthosite mass, following the windings of the boundary, and that it is not entirely an original structure, in consequence of which the anorthosite mass took its present outline, but it is in part at least secondary, having been caused by the great pressure to which both rocks have lieen subjected 8ubse<|uent to the intrusion of the anorthosite mass, which pressure has induced a cert^iin amount of motion in l>oth rocks. This motion has been accom- panied by a certain stretching, dragging, or flowing of the gneissic series along the edge of the anorthosite, as seen especiiUy well in the abrupt change in strike of the gneisses along the immediate margin of the anorthosite mass about I^ake Croche and to the north-east of Ij«ike Ouareau. That a stretching of the gneissic series has taken place, is also clearly Stn tdiiinf of proved in many places where the ordinary ijuartzose orthoclase-gneiss H,.',.i,fJ."""^" alternates with bands of dark pyroxene-granulite or amphibolite. In such cases the dark bands are often seen to have been pulled apart, the disconnected pieces being arranged in lines following the strike of the rock, and can l)e plainly seen by thf fact that the ends of adjacent pieces match one another, to have oi iuiiially formed parts of the same band. The accompanying sketch t iken from an exposure on the Cyjiress Hiver, a short distance beyond the northerly limit of the map, sh(»ws this excellently. Here there are large exposures of fine-grained reddish (|unrtz orthoclase-gneiss, with bands of a basic bands becomes more marked and very strik- ing and seems to be the invariable rule whenever rocks of this char- acter are associated with (juartzose gneisses and the whole series is bent or twisted. The same phenomenon is very well seen in the case of the thin bands of gneiss, so frequently found interstratitied with the lime- stone bands. Here the limestone under the influence of pressure is the more plastic of the two rocks, and the gneiss, also plastic to a lesser extent, is bent into curiously complicated forms, but when the movements Ijecome too great is torn apart into curved and crumpled fragments, which, stiinding out from the weathered surface, give the rock a very remarkable and characteristic appearance. It may appear somewhat remarkable, in view of the folding to which these rocks have been subjected, that faults are not more numerous. They seem, however, to be i-are, although in such areas of contorted crystalline rocks, their existence is not easily determined. Only two were noted, although the existence of others was conjectuied. The first of these is at the dam on the River Ouareau, where it flows out of Lake Ouareau. Here, two masses of red orthochuse-gneiss, with interstratified quartzite bands, come together, one set striking N. 10° W. and the other N. 40° E., both having a high south dip. This it will be noted is a portion of the area where the compression of the gneiss must have been especially severe, the ordinary north-westerly strike of the country-rock being changed to a north-easterly strike along the margin of the anorthosite mass. The second fault which was noted is on the road between New Glasgow and St. Calixte de Kilkenny, about six miles in a straight line from the former place, and at the contact between the gneiss and the anorthosite, where a fault probably occupies the bed of the River Achigan, one conspicuous band of gabbro running up to the river and there disappearing. Faults. lartzose rocks nents. Some- /ery consider- ;tching can be astern part of ving apart in a sucli as might he underlying a great weight exerted by the )uth-west, this ind very strik- 1 of this char- whole series is ,se of the thiii vith the linie- of pressure is Iso plastic to a 5, l)ut when the d and crumpled urface, give the folding to which uore numerous, as of contorted ned. Only two njectured. Tlie iiere it flows out liise-gneiss, with striking N. 10' h dip. This it ipression of the ' north-westerly li-easterly strike and fault which d St. Calixte de armer place, and ;e, where a fault one conspicuous ppearing. ■] STRATir.RAPHICAL KELATION.S. 17 J The fact that these rocks have been folded rather than faulted, does rniKlitionsof not seem so remarkable when it is remembered that the movements to '"' '"*^' which they were subjected were brought about when the rocks were deeply buried and hence 'ea\ily loaded. Heim has shown folding rather than faulting to be the result of such conditioi.s in the Alps. The fact that the rocks, when subjected to these movements, were in a iiighly heated condition, as will be shown in treating of the anortiio- sites, probably convributed to the same result. The alternation of the various varieties of ortlioclaae-gneiss with one another is especially well displayed in the township of Brandon whei-e also there are very numerous anrl heavy bands of pyroxene-gran ulite, as well as several bands of anorthosite (p. 126.1) conforming to the general strike. The township, therefore, merits a short, special description. The first ten ranges are for the most part cleared and settled, while the last two ranges are still largely under forest, the country rising to the north and being there more rugged. Un- fortunately muck of the southeastern part is heavily drifted so that over considerable areas no exposures can be seen. A striking feature of the eastern part of the township is the beauti- ful stretch of water known as Lake Maskinonge, with its extensive valley of flat drift extending northward through the 8th and 9th ranges and indicating a much greater extension of the lake in this direction in post-glacial times, l^ic Corbeau and Lac Noir have also, as seen in the presence of similar drifted valleys, been much larger sheets of water in former times. The township is traversed by numer- ous roiids which afford means of access to almost every part of it, and owing to the way in which it is laid out, the ranges running north-east and south-west, while the rocks strike north-west, the roads running between the I'angcs afford a series of lines of section directly across the strike. In geological structure the township may be divided into two parts, Town- one consisting of the north-west two-thirds and the other of the south- east portion comprising the remaining one-third. Tlie north-west portion is occupied by a flat syncline, the rocks striking north-west, those of tiie eastern half of the township dipping at low angles, averaging about 2o\ to the south-west, while those in the western half dip to the north-east at angles of about 15^ (see accompanying section, Kig. 3.) In the two upper ranges, the strata over considerable areas arc ((uite flat, and no dip exceeff syd""'. : arnetiferous gneisses of various kinds, with occasional silliminate- yneisses. Also heavy bands of pyroxene-granulite and pyroxeue- amphibclite, with bands of quartzite and three bands of anorthosite. A section across the township along the line between ranges VIII and TX. a distance of eight miles, is seen in Figure 3, and detailed petro- graphical descriptions of the several rocks are given on pages 38 J, 76 .t. 'I'liese various rocks have the form of distinct bands which are usually sharply ilefined. No limestone occurs in this townsliip. The rocks, as for instance granulite and pyroxene-granulite, often alternate in bands much too thin to be separately mapped, and the individual masses, even if of large size, frequently pinch out or alter their character in the direction of the strike, and the drifted character of the basin of Lake Maskimjnge renders it inipossible to ascertain whether the several grcjups of rocks recognized in tlie western half of the section reappear in regular order to the east of the synclinal axis. The anorthosites, however, wete nowhere observed on this side, which indicates that they are • it interstratified layers but rather squeezed out intrusive masses and ti 3 exposures wliich are seen on the eastein half of the section indicate that the rocks here present fewer varieties. It is probable, however, that the fact that certain well-defined bands which appear in the western half of the section do not reappear to the east of the synclinal axis is due to the series being essentially a rolled out complex of igneous masses. The exact thickness of the " strata " represented in this north-west portion of the township is not known, but, as has been mentioned, the country grtidually rises to the north, and it was ascertained by direct measurement (aneroid), that starting from the edge of the drift-filled basin of I^ake Maskinonge, at lot 6 on the concession line between ranges IX. and X., and going north to a point about the middle of lot 1 of range XII., the ascent is made over 540 feet of nearly horizontal strata ; if the average dip of these be taken at 15° this alone would represent a thickness of 522 feet. The evidence here, as in other parts of the area where the gneisses are approximately horizontal, goes to show that although the bands are not flexed and contorted they have been subject to great vertical compression. The various, rocks are quite as highly crystalline as in 20 .1 QUEUE*'. I ! ' the more contorted districts, the anorthosites show evidence of very great crushing since they were injected, and the gneisses themselves under the microscope show very marked cataclastic structure. Granite inasH The south-east portion of the township is quite different in structure At tlie extreme south-east corner is a small area occupied by a portion of tiie great granite mass which occurs along tlie eastern side of the '• sheet. It is coarse in grain and sometimes possesses an indistinct folia- tion. Limiting this granite on the west is a band of fine-grained granite about a mile and a half wide. It is (juartzose and reddish in colour, almost fiee from mica or other iron-magnesia silicates, and nearly uniform in grain and composition. In many places one can observe little local irregularities in grain such as are often seen in granite apophyses, and it frequently holds loj'ge orthoclase phenocrysts like the coarse granite to the east. In many places an indistinct foliation can be .seen, and it often liolds little strings anci sometimes apparent fragments of white quartzite and of a dark basic rock, usually coinciding in direction with the indistinct foliation above mentioned, which is about N. 5^ W. and parallel to the limit of the coarse-grained granite. This finis-grained granite is apparently a contact phase of the coarse granite, the transition, however, being very rapid, since on lot I of range III. the two can be seen within a few yards of one another. An actual contact or passage between them was nowhere observed. The western limit of this fine- grained granite, on the line between ranges I. and II., is about the east half of lot 8. To the west of this the fine-grained granite is succeeded in the following lot by a well-banded grayish gneiss, striking N. 10 W. and dipping to the east at an angle of (55". In this area are many dykes, veins or bands of granite, often very coarsely grained as is .so generally the case in pegmatite apophy.ses, sometimes running parallel to the banding of the gneiss and elsewhere across it and anastomosing with one another. This gneiss is exposed at fre<|uent intervals along the road for a distance of rather over three miles from the fine-arained granite, but is usually reddish in colour and holds bands of (juartzose and hornblendic gneiss, fretjuently broken uj) into fragments, which, altiiough in many cases evidently having formed parts of the same band, now lie in the reddish gneiss separated fiom one another. This reddish gneiss in many places resemliles the fine-grained granite and is almost free from iron-magnesia minerals. The strike of the gneiss varies very much in different places, and even in the same exposure. It, however, always dips in an easterly direction or towards ] STRATir.RAPIIICAL RELATIONS. 21 J the granite, and always at very liigh angles of from 65 to vertical. From the last exposure of the gneiss on lot 17 to the western limit of the township, there are no other exposures, the country being heavily drifted. , In the south-east corner of the township, therefore, we have the edge of a great mass of granite Hanked by a band of much finer grained granite, and beyond this a series of highly tilted gneisses, which have been much disturlted, and penetrated by granite veins or dykes api)arently apophyses from the main mass, the .series being entirely different both in character and attitude from the well-banded gneisses of the Hat syncline occupying the north-western portion of the town- ship. Between these two areas the township is under heavy tlrift, so tiiat the actual relation of the two sets of gneisses to one another is oi)scured. It would .seem, however, that they must be separated by some stratigraphical break, either a fault or an unconformity. It may be noted that if' a lini^ be drawn from the most westerly exposure of these south-eastern gnei.sses, on lot 17, to the northern point of Lake Maskinongt', it will divide the two series from one another, and such a line would al.so run nearly parallel to the limits of the granite mass. The north-western gneisses belong to the Grenville ."-eries ; whether tiie south-eastern gneisses should be referred to the "fundamental gneiss " or not is uncertain. Among the most important constituents of the Grenville series, not so much on account of their volume as owing to their economic value and the genetic considerations attached to them, as well as to the aid which they allord in working out the stratigraphical relations of the .series, are the crystalline limestones. The existence of bands of crystalline limestone in the Hat-lying gneisses, beyond the north-east- ern limit of the map, has already been referred to, but within the area embraced by the map, although not observed in the nearly horizontal gneisses of the north eastern districrt, crystalline limestone is repeat- edly exposed el.sewheic, as will be seen by consulting the map, being brought up by the folding of the jinei.sses in the more contorted parts of the area. The south-western portion of the area embraced by the map, insoutli-wf as has already been mentioned, was included in a "Map Showing |^"'''''''''''^ the Distribution of the l.aurentian Rocks in Parts of the Coun- ties of Ottawa, Terreljonne, Argenteuil and Two Mountains," by Sir William Logan, published in the Atlas accompanying the "Geology of Canada," which appeared in 1865. In the map accompanying the present Report, the distribution of the limestones in Montcalm, Orystiilline liiiit'stdiies. ''■ fi'i li^ , l.-l 22 J (jUEUi:c. Morin, the Augmentation of Mille Isles, and in the district to the aouth-west hus been taken from this map. In the area worked out by Logan, which, however, lay principally beyond the western limits of the present map, he believed that the existence of eitlier three or four distinct limestone bunds of considerable size, at widely separated liorizons, tould be established with tolerable certainty. Dr. Klls, how- ever, who has recently re-examined this district, and whose report will appear shortly, doubts the correctness of these views, and believes that the limestones are concentrated towards the summit of the series. The character and distribution of the limestones in this portion of the area being described in the reports of Logan and Ells, need not here be further referred to. In the narth-w^st corner of the area, the Laurentian is represented by reddish and gray gneisses, often rich in (juartz and well foliated, whicli on the Devil's Hiver are occasionally garnetiferous and associ- ated with quartzites. This district is a good deal drift-covered, and no crystalline limestone was observed in j»lace, but a large angular block of this rock found by the side of the Devil's Hiver, about the northern limit of the map, indicates that bands of this rock do occur here associated with the gneiss. A heavy band of limestone runs through Trembling Lake, which lies immediately west of Trembling Mountain, being ex|tosed on the islands in the lake as well as at its outlet. Crystalline limestone is also exposed at several points in the vicinity of St. Jovite, in the township of De Salaberry, but the heavy drift which mantles this portion of the country renders it impossible to ascertain the extent and distribution of the rock. In that portion of the district to the east of the .Morin anorthosite, it was al-so believed at first that some five or six different bands of limestone existed, but the result of a detailed study goes to show that the three principal bands at least are probably repetitions of one and the same horizon, being related to one another as shown in the sections accompanying the map. The course of the several lines of outcrop of thesi :-a.^ie.n limestones may be briefly indicated. Crystnlliiip There is first a small and compai-atively unimportant occurrence on St" Sn"™'^ *^« ^^«s* ^'^e of the North River, near St. Jerrtme. Exposures of the limestone are seen crossing the road, and blocks of it may be found at intervals in the fields to the south of the road. Logan states that it can be traced for about a mile and a half, running in a direction Crystalline limt'stonc of Treiiililinp Lake. ] STRATinKAPillOAL BELATIONS. 23 J istrict to the a worked out western limits itliei- three or ely separated Dr. Klls, liow- »se repftrt will believes that of the series, jortion of the need not here is represented well toliat«'d, us and associ- overed, and no angular Itlock t the nortliern do occur here g Lake, which x|to8ed on the io limestone is Jovite, in the 1 mantles this lin the extent in anorthosite, jrent bands of !S to show that ns of one and in the sections u-.n limestones occurrence on {posures of the ay be found at states that it in a direction N. 12° E. Although the surrounding country was carefully examimd, no actual exposures of this limestone could be found, except those above-mentioned. In the direction of its strike to the south, it would (TOSS the North River and be covered up by the Cambro-Silurian rocks within the next half mile. It does not appear on the banks of the river, however, neither could any continuation of it be found to the north. A more important occurrence of limestone, although still conipara- NVur Ntw tively thin and impure, is found a short distance to the west of the village of New Glasgow, being exposed in the bed of the River Jordan and near the Cambro-Silurian contact. From this pnint it can be traced in a direction a little east of north, skirting along the edge of the great anorthosite arm, as far as range III. of Kilkenny, a distance of about six mile«, where it is lost sight of. " ' An isolated exposure of a pure white crystalline limestone occurs On lot 10, range VII., of Kilkenny, where it forms a low ridge about a hundred yards wide. This, however, is probably distinct from the New (jrlasgow band, which, if it holds its course as above described, would l)e cut off by the anorthosite a short distance to the north of the point where it is last exposed. It certainly is cut oflp by the anorthosite eventually, for the latter on the north passes across the strike of the gneissic series. What may be a continuation of this same limestone band, however, appears on the other side of the anortho- site mass, at Lake Ouareau. The most northerly point at which the limestone is here exposed, is a slight elevation rising above the drift on the Couture Road, on lot 20, range II., of Lussier. Following the prevailing strike, it appears again to the south-east, in Lake Ouareau, forming a series of little island.s, which lie along the west shore of the lake. On one of these, which is composed exclusively of white crystal- line limestone, with many little inclusions of gneiss produced by the tearing apart of narrow liands in the manner already described, the strike is about N. 75 W., and the limestone is exjmsed for a width of 275 yards acro.ss the strike. This is not the whole width of the band as the exposure is bounded by the waters of the lake on either side. The band then appears on the east shore of the lake, near its southern extremity, where it has a width of about 200 yards. The southern portion of the lake is, in fact, excavated in a band of limestone, inter- stratified with white quartzite and certain gneisses which are almost invariably found associated with the limestones, which band, being very near the border of the anorthosite mass is, at many places all about the lake, invaded by and mixed up with anorthosite, which is At Lakf < Itiiirt'au. ,>■• i it I .- ,». ■''I .,* V I m f'U 24 J QUEBEC. CryHtnlliiic liiMHHtciiif ii Catlicart. often intruded parallel to the foliation of tlie gneiss, and often has a more or less distinct foliation accompanied by excellent cataclastic structure (section 370). The fact that it was possible to point out the existence of limestone in this remote district was of considerable importance to the settlers there, who had been obliged previously to haul all their lime from St. Jt-rfime, a distance of forty miles over rough roads. The strike, wherever this can be observed, indicates a sharp bending of the strata back upon themselves at the southern poition of the lake, corresponding to the outline of the lake. The foliation is prob- ably largely a secondary one, induced by pressure, iis shown by the fact that it is shared by the intruded anorthosite. The limestone with its associated gneisses is limited on three sides by the anortho- site, and here again is evidently cut off by it. A second limestone band occurring to the east of the Morin anor- thosite, is seen in the bed of the Black River, on the line between ranges VIII. and IX. of the township of llawdon ; then in large exposures on ranges IX., X. and XI. of the same township, crossing into ranges III. and IV. of the Augmentation of Kildare, on the western corner of that townshijt. Going still further north, it is .seen on lot 11 of range IV^. of Catheart, crossing range V^II. of Catlicart and running under a little lake on range VIII., appears again near St. Come, and is then exposed on lots 27 and 28 of the last range of the township of Catlicart. To the north of this point the country is unsettled, and covered with a dense growth of forest, so that the continuous tracing out of a small band of limestone is impossible. Continuing on the j-aine strike, however, limestone was observed on the front of lot 28 of range II. of Cai'tier, on the line between IT. and III. of Carrier, also about lot 28, and then at two points on two little lakes lying a short distance to the east of Lac des Ilets on the stream issuing from that lake. Limestone was also observed protruding through the drift by the .shore of the Hiver L'Assomptioii, about four miles from Lake L'Assoniption. It is here exposed for a width of fifteen feet across the strike, but the limit of the band is seen only on one side, the water concealing its contact with the gneisses on the other. The petrographical character of this limestone is described on page 66 .i. This occurrence, however, is not on the same strike and may not belong to the band above described. It was impossible to follow this band with certainty in its .southerly extension. This is owing to the fact that the southern part of the town- ship of Rawdon is heavily drift-covered, comparatively little rock being 1 STRATItiRAPHICAL HKI-ATIOXS. a.* .1 md often has a ent cntaclastic B to point out of considerable I previously to irty miles i)ver t sharp bending piiition of the sliation is proh- 18 shown by the The limestone by the anortho- he Morin anor- le line between ; then in large •vnship, crossing Kildarc, on the north, it is seen IT. of Cathcart ears again near the last range 3int the country rest, so that the e is impossible. vas observed on between IT. and nts on two little ,s on the stream )truding through t four n)iles from ifteen feet across »n one side, the the other. The ed on page 66 .i. ie and may not y in its .southerly part of tl>e town- f little rock being o.\|)Osed. Mr. Carlyle carefully examined the River Ouareau, from Hawdon to the Cambro-Silurian contact, and was unable to find any lime.stoiie. Altove the village, the river runs through drift, until the exposure of anorthosite at the upper bridge is reached. Small ex- posures of the limestone were, however, found protruding through the drift, on range IV. of Hawdon, about lot 13, which may possibly mark a continuation of the band in this direction, but if so, the limestone l)and is greatly diminished in si/e to the .south. Tliis band, which may be called the Uawdon l)and, is most exten- Hiiwduti sively exposed on range TX. of Uawdon, and in the vicinity of St. ''•""'• t'ome. At ti:e former locality, several years ago, it was extensively liurned for lime, and at the latter place it is now being burned at two different points. A noteworthy fact in connection with this limestone band, is that it occupies the sunnnit of an anticline, the dip being from it on either side. A third band is seen in considerable exposures about a mile and a iialf west of St. Alphonse, on range T. of Cathcart, where it is J)urned for lime, and to the south on tiie adjoining range of the Augmentation of Kildare. It is then .seen near the road, al)out lot 38 of range VI. of Cathcart, and then at a numl)er of places lying in a direction west of north from the last exposure and running througli langes VII., VIII. and TX. of the same township, it passes into the forest covered township of Tracy. The fourth band is thin and impure. A few exposures about a mile to the south-west of .St. Ambroi.se de Kildare may probably i>e referred to it, but it is well expo,sed first, on range VII. of Kildar ■, near the cheese factory, then about the rear of this township, then in the village of Ste. lieatrix, and again about a mile further north, at the bend of the River L'Assomption. Then in the Seigniory of the D'Aillebout, about three miles south of Ste. Emilie, and again on the Mattawin load, about the line Ijetween ranges III. and IV. of .Toliette. A fifth band, still further to the east, is exjio.sed on lot 2, of range fivstiilliiif VII. of Kildare, and is then covered with drift until it reappears litixstonc in • 1.1 1 • I , 4 -1 • 1 Kil'ii'i'i'. about three miles further north, in D Argenteuil, at a point one mile east of the town-line of Kildare. These several bands, together with tho.se described in the south- other eastern portion of the area by Sir William Logan, einl>race all the <>c'^'""''iii'''i'. limestones which occur in it, with the exception of four small isolated OLCurrences. The first of these has been already mentioned, and is i -.■1,1 illi ;il I '1 ■ 1- J ■ ' 'P ! ■' i m * ■I'd 26 J QUEBEC. If; fdiitiimity of till' liiiicstcinc sitiKvted on lot 10 of range VII. of Kilkenny. The secoml whs found on lot 22 of range IX. of Rawdon. It is about twenty feet wide, and is associated with a band of nearly pure, coarsely-granular, pyroxene rock, which is described on page 85 .i. Its mode of occurrence is that of a lenticular mass. The third is on lot 20 of range V. of Rawdon. T^e fourth occurrence is found near the line between lota 8 and 9 of range VI. of Cathcart. This has i)een opened as a niarOie quarry, and pirtakes rather of the nature of a vein deposit. It is described on page 152 ,i, in the section treating of the Economic (ieology of the district. The (|uestion as to whether the Laurent ian limestones form con- tinuous bands or are merely a series of disconnected lenticular masses has been frequently discussed. Tiieir softness and the ease with which they are eroded makes these limestones appear less continuous than they really are, for glacial and pre-glucial decay and erosion acted far more vigorously on the limestone bands and the strata immediately associated with them than on the harder gneiss of the series, and as a result the former almost invariably f ,>~'ipy depre.ssions, and very frequently river-valleys or lake beds. In such places, of course, the drift is thickest and most persistent. When, therefore, the strata un;lerlying such a drifted area are contorted and only proti-ude at intervals through the gneiss, or even when they are not contorted but exposed only at considerable intervals, it bt^comes a matter of great ditiiculty t > decide whether the occurrences of limestoni' form a continuous band of limestone or a series of discoimected patches. 1 1 becomes, however, necessary in this connection to th^fine what is meant by the terra "limestone band." Pure crystalline limestone or marble, ten, twenty to sometimes 100 or more feet in thickness, is often found, bui in the majority of ca.ses the bands consist of the limestone inter- stratitled with many thin bands of gneiss. This was true of all the limestone bands described by Sir William Logan in the "Geology of Canada," the gneiss often constituting half or more than half of the whole thickness. When by squeezing or stretching the.se gneiss bands have bi en torn .apart or pulled out into fragments, the gneiss and limestone become irregulaily mingled together; subordinate ma.sses of limestone may disappear along the strike and gnei.ss may come in, to be succeeded again by limestones. The limestone also being very plastic under pressure, the relative amounts of the two rorks may vary in different parts of the band. The band as a whole may thus be continuous for a long distance, while its individual comj)onent masses may and do thin out, disappear. 1 HTRATKIKAHIIICAL KEhATIONH. '.I .1 iml WHS found feet wi«l»', and ular, pyroxene if occurrence is )f rangt! V. of le between lota led as a uiari)le deposit. It is the Keononiic .ones form con- 3nticular masses the ease with ■ less continuous ,nd erosion acted ata immediately he series, and as ssions, and very 3«, of course, the Bfore, the strata )nly protrude at lot contorted but matter of great imestona form a eted patches. It ine what is meant estone or marble, iss, is often found, le limestone inter- ,s true of all the the "Geology of than half of the these gneiss bantls ,s, the gneiss and ordinate masses of ss may come in, to e also being very le two rocks may jr a long distance, thin out, disappear, MllVl'IIH'lltH litiii'stonc IhiikIh, and becom'! succeeded by others. It is tlius by no means uncommon to Hnd a limestone band which, at one part of its course, is represented liy a thick development of nearly pure limestone, further on represented hy a number of thin layers of limestone interstratified with bands of gneiss. A limestone band thus Imcomes a certain horizon more or less thick in which limestone is abundant, while it is absent from the rocks on either side. Accepting the term " limestone band " in this sense, investigations in this area go to show that when the country is favourable for study, limestone bands are foumi to be continuous for long distances following the strike of the associated rocks, and that they are at least as conti- nuous as the bands of any other kind of rock making up the series. Hut, as before mentioned, their very nature causes them to be more easily iiidden or drift-covered, than the bands of the harder associated rocks, and they are thus .sometimes apparently less continuous than these. There is reason to believe that the limestone bands sometimes act as lines of least resistance along which motion is especially pronounced under the diflerential strams incident to folding. An e.xcelleiit ex- ample of this, on a small scale, was seen in an exposure about one mile south-east of a point two miles below the Ox-bow Rapids, on the Uiver Mattawin, in the region of flat-lying gneisses beyond the north- ern limit of the map. Here the gneiss is usually medium in grain and is to all appearance as well bedded as any sedimentary .series. Several little bands of crystalline limestone, from a few inches to two feet in thickness, together with a few small bands of (juartzite, are interstrati lied with the gneiss. An excellent section is presented in the cliff by the side of a little brook, and the effects of a thrust in a directicm jtarallel to the bedding, conse(juent on the stretching to which the rocks in this district have been subjected, is well displayed. The upp"r beds can be plaiidy seen to have moved for a few feet over the low<>r beds, along the plane of a thin limestone band, which, with its interstratified gneiss layer.s, is quite undisturbed in the northern end of the section, while further south it has been bioken off, folded on itself, and puckered up in a most complicated manner by the hori- zontal motion. The thickest body of limestone exposed in the area is probably that Tjiuktst ImkIv on the islands of Lake Ouareau, which, as above mentioned, has a width "275 yards across the strike, with neither wall seen. The largest occurrence of pure limestone, unmixed with gneiss, uncontorted and dipping regularly, so that its true thickness can be ascertained, is a portion of the Rawdon band, on lots 27 and 28 of range X. of Raw- I'l J! •/: !)| ns gl'RHEC. ilod, ill the vftlloy of ii brunch of tlic River l{ouge. Hills of KiieisM rine on either "itle of the river iit tliis point, those to tlie west also holding some limestone, and between tliem is ii neiirly level in»ervftl through which the river runs. This strip or interval is 2"jrt yards wide, and is in all probability entirely occupied by the limestone band, which, in that case, would here be about double its (Mthcr all t\wHt> gnciHSON leiilly t'«)rm ii {lurtion of ii thtor on wliich tlic rit*H wah determined. Aiid IntriiHlons. Two lar^o iind important intrusions of acid plutonic rock break liitiiitf association with the limestone bands, and it is the exception to find crystalline limestone unaccompaniect by this gneiss. It occurs not only in many i)arts of the area at present under discussion, but in every other part of Canada and the United States where the Grenville series with its characteristic limestones is found. It is especially well devel- oped in central Ontario* and about Port Henry in the State of New York. The quartzite, often garnetiferous, also occurs, chiefly in association with the limestones. A noticeable feature in those Laurentian gneisses which have c|uart/, and orthoclase as the chief constituents, is the small proportion of iron- nuignesia minerals which they contain. It is rare to find such a gneiss rich in these constituents, and very frequently they are entirely absent. On the whole, hornblcmle is more common than biotite. The colour of the ordinary gneiss on a fresh fracture is reddish or grayish. The more basic varieties are dark-gray or even brown in colour, while in the acid gneis^es, reddish and light-gray tints prevail. Tiie gneisses weather white, gray, reddish, or brown, according tothdir composition. They are occasionally very coarse-grained, especially in the case of the augen gneisses, which sometimes hold masses of fel- sp;ii', an inch or more in dianietei". They are generally however medium in u'l'ain, oft«iii fine-grained, but seldom so fine that the chief constitu- ents cannot be distinguished by the unaided eye, especially when the weatliered surface is exn mined. As has been stated above, the distinctive chai-acteristic of all these iMiliiaicm uml gneisses is the possession of a more or less decided foliation or banded ' ' *" structure. By foliation is understood a laminated structure, produced in a lock by the parallel arrangement of certain or all of its constitu- ent minerals. Thus a granite would become foliated if all the little biotite individuals were caused to assume a parallel position, and the foliation would become still more pronounced if the other constituents were also arranged in parallel strings. By banding is understood the alternation in the form of bands, of gneisses difi'ering more or leas in composition or structure, which gneisses may or may not be foliated as well. The t)rigin of this foliated or banded structure in the case of the Archa-an is one of the most difficult problems presented in the study of these ancient rocks. lb was formerly supposed to represent the •F. I). AdftiiiN, — He|K)rt on the ( J(>olo(fy of n portion of Ccntnil Ontario, Annual l{i-|)ort, (Jt'ol. Suiv. Can., Vol. VI. (N.S.), 1892-93. 3 '- ' ••'■.ij 'I'i ■i- ■[ ■■■ > '.^ - . 1-f*| ■}■ 34 ,) yl'EBEC. *1 Tts oriKiii. Altered sedimeiitsi Crushed iijneim& rooks. remains of an original bedding, due to sedimentation, but now almost obliterated, the gneiss thus being comparable to certain indistinctly foliated rocks found in contact zones about great eruptive masses of granite. In recent years, however, the study by many able investiga- tors* of the effects produced in rocks when deeply buried in the earth's crust and subjected to great pressure during the process of mountain making, have clearly shown that perfectly foliated rocks may be and are produced from massive igneous rocks, by such processes, so that the existence of a foliated structuie in a rock can no longer be regarded as evidence of sedimentary origin. Any rock when subjected to defor- mation under the influence of prtjssure, will tend to assume a foliated character. If theseniovements have been very pronounced, thefoliation will be correspondingly distinct ; while, if the pressure has acted on a complicated series of rocks of diverse character, as for instance igneous and sedimentary rocks penetrated by later intrusions, or on a great Ijody of igneous rock which has undergone magmatic diflerentiation, a petro- graphical series composed of alternating bands of very different varieties of gneissic rocks may result. The great irregularities in composition which of recent years have been shown to exist in many large eruptive masses, make the intimate association of different varieties of gneiss, and their passage into one another, much more intelligible than formerly, since such associations and gradual transitions would certainly be presented in any gnei-sic series formed by the .squeezing or stretching of differentiated masses of this kind. Thus, in several districts of ancient crystalline rocks which in recent years have been made the subject of very careful study, as for instance the granulite region of Saxony and the .southern portion of the Grand Duchy of Baden, a great weight of evidence has been accumulated which goes to show that certain rocks which have been classed as Archa-an gnei.sses or schists are altered sedimentary rocks, while other gneis.ses in the same districts can be shown to be squeezed or crushed rocks of igneous origin. The separation and recognition of these two classes of rocks will probably become more easy and certain as investigation advances, but it remains to be ascertained whether it will be possible eventually to bring all gneisses under one or other of the.se two heads. * A. Hfim.— (ieolofrie der Hiiclialpen /.wiscficn KeusK iind Rliein.-Heitriitfi' zur (!eol. Karte der Scliweiz, vol. XXV. Bern, ISitl. C. Schmidt. —Hi'itriige 7,ur KeniitniHH der auftif>tciidon Gt'dteinc. II). B. Milch.— Bcitriigo zur Kt'iintiiLsH dew Verrucauo. ErstcrTlieil. Leipzig, 1892, and many others. ana ] PKTttOORAPUV OF THE LAURENTIAX. 35 .1 nd Rlieiii.-BMtriigc znr The criteria for the determination of gneisses which consist of Critiiia for metamorphosed sediments are not as yet thor()U^i^'lIml rounded, water-worn pebbles, or angular clastic quartz grains, when recognized in any crystalline rock, also determine it to have been of .sedimentary origin. In this way, certain rocks in Norway and Saxony formerly classed as Archtwan crystalline schists have been recognized as altered congiomeratte. Clastic quartz grains are in some cases rendered possible of recognition by the fact that in the processes of alteration secondary silica is deposited about them, and in this way the form of the original grain marked by its coating of iron oxide or other adhering impurity, is preserved and can be recognized, notwithstand- ing the complete alteration and crystallization of the rock. This process is especially well seen in the case of sandstones changing into (juartzites, but can also be recognized in the metamorphisra of certain arkoses into felspathic quartzites, which in composition would be identical with the more acid gneisses of the Archa-an. Applying these tests in the district at pre.sent under consideration, it has been found possible to place in one class certain locks which all lines of evidence indicate as of sedimentary origin. To these belong the crystalline limestones, the quartzites, and certain associated gneisses usually containing sillimanite, garnet, and graphite. Another class can be recognized as consisting of rocks of igneous origin which have been squeezed or crushed. To this class, in addition to the anorthosites which are treated by themselves under another heading, are a whole series of quartzose orthoclase-gneisses, usually |ioor in iron-magnesia constituents, and possessing a variety of struc- tures. A thii'd class consists of rocks whose origin is as yet doubtful. This is due in part to die fact that, it has been impossible to su'^'sct them to an exhaustive examination, including chemical analysis. Possibly, however, their origin could not in many cases beuascertained even if such an examination were made. This class includes a considerable proportion of the ordinary orthoclase-gneisses of the district, as well as most of the pyroxene-gneisses and amphibolites. Kocks iif (lonl)tful origin. ' (ieoloifiMche Sjieciiilkarte des GrcwwlHTzogtliuiiis Badt'ii — Krlaiiteruiigeii z\i Blutt < !eiigt'iil>ach von A. Siu\t>r— HeidcUierg, 1894, page 8. i \\ i-i; 1 :/j U' ■ ii/il i ' 'ri 38 .1 QUEBEC. sii' i; 4i A-ugen-tfiii'iss, In the foUowiiif; pages these three classes of rocks will be considered separately, beginning with the gneisses of igneous origin. Instead of endeavouring to describe every member oi the large suite of specimens which has been studied microscopically in the course of this investigation, which would entail the presentation and repetition of an immense mass of petrographical detail, a number of typical occur- rences from each class will be selected for description, as it is believed in this way a knowledge of the petrography of the district may be more clearly conveyed. C/aas J. — Gneissi'x of lytieuiis Oritjin. In these gneisses, orthoclase felspar preponderates largely, which is itself evidence against a sedimentary origin. Quartz is almost always present, though frequently in small amount. Its presence and j)ropor- tion can be best ascertained in the field, by an examination of the weathered surface of the rock, on which the contrast of the quait/ anil orthoclase is much more marked than on a fresh fracture. These two minerals frecjuently make up almost the entire rock (quartz-orthoclase- gneisses), but they are usually associated with suiall quantities of biotite and hornblende, occurring either separately or together, (irapliite, which is abundant in rocks of class 2, is never found in these gneisses. Three structural varieties are especially worthy of mention : («) Augen-gneiss ; (i) Ordinary granulated gneiss ; (c) Leaf-gneiss. These are connected by transitional forms. Angeu-dneiss (Quartz-Ovthoclase-IIornblendi'-Gtieisx) — 7\»cns/iiji of' Brandon, Lots 16 and 17, Kunge IX. (Siclion ooo). The rock is of a reddish colour and ((uite uniform in character over large exposures. In hand specimens, it shows a distinct foliation caused by the presence of slightly undulating but nearly parallel nai- row black lines of hornblende, alternating with thicker streaks and layers of reddish orthoclase. These minerals occur for the most part in the form of fine grains, but in this finely granular mass cores or remnants of large individuals of hornblende and orthoclase respectively are abundant, from the granulation of which the finer grained portion of the rock has been produced. These cores have not a good crystalline form, but are rounded, lenticular, or tear-shaped, with trails of the granulated material running off from them in the direction of the foliation on either side, the foliation curving around them. The orthoclase cores be considered he large suite the course of iiid repetition typical OLcur- i it is believed t may be more rgely, which is almost always ici- and propor- lination of the the quartz anil re. These two lartz-orthoclase- ititiesof biotite her. (Jraphite, I these gneisses. mention : («) nif-gneiss. — Townahip of n oil')). n character over istinct foliation rly parallel nar- ker streaks and ij of tine grains, large individuals lulant, from the he rock has been e form, but are the granulated the foliation on orthoclase cores ■1 PETH0(iHAPHY OF THE LAUUENTIAN. 39 J are often large, sometimes over an inch in diameter, frequently pre- senting curved or twisted faces, and can be seen to be in the very act of breaking up into smaller fragments. The hornblende remnants are identical in shape with those of the orthoclase, but are smaller in size. Under the microscope the rock is .seen to be composed essentially of eripheral granulation, as described in the ca.se of the anorthosites. The groundmass, .so to speak, in which these orthoclase augen are embedded, consists principally of small grains of the same mineral. These generally show the same mottled appearance as the augen, and differ but little from one another in size. The larger ones often exhibit an uneven extinction ami can fretjuently be seen to be in the act of breaking up into smaller grains. All these smallei' orthoclase grains ^re very irregular in shape. In one of the sections a very few small grains of plagioclase were present. The quartz occurs chiefly in more or less elongated grains. These are often greatly elongated, t'orming the "leaves ' of quartz so abundant in the "leaf -gneiss.' These are distributed through the granulated oithoclase lying in the direction of, and in fact in part causing, the foliation of the rock. These giains have an almost uniform extinction, and are not broken or granulated, even if they are many times as long as they are wide. On very careful examination, however, they can usually be seen to exhibit a slightly uneven extinction suggestive, as will be shown in describing the •"leaf gneisses " of a smearing of the mineral out in one plane. They sometimes fork at the extremities or at the sides. The.se (juart/ individuals can often be observed sweeping around the partially gr.inulated augen of orthoclase in long curved grains or lines of grains. The hornblertde, which is green in colour and is present in com- paratively small amount, occuis as strings of very irregular-shaped H ihi. '■■ 4. -I \ ■ ,r vit. I; ■ ]i I 3 vim i i? r h 11 ^1 m Rni II •I .Mi«lf of OCCUITfllcr. Orijfin. 40 .1 QIKHEC. gittins, resulting' from the granulation of larj,'e individuals the cores or remnants of which remain as small augen. A grain or two of biotite is occasionally associated with the hornblende. In one slide a sifigle grain of diallage was present, but in all the slides there are a few grains of a yellowish aggregate, which is apparently a decomposition pros tliroiigli wliicli tlicy cMit. 'riiis cxiMisiirc is S ffft in wiiltli. (Range VI., I^ot 17, TowMsliiii of lirandrxi.) At this locality there is a .series of large roche moutonnt^ exposures made up of an alternation of tine-grained, reddish, orthoclase-gneiss, coarse augen-gnei.ss, dark pyroxene-granulite, and vitreous «|uar/.tite, the whole dipping to the east at a low angle. Although the several rocks seem at the first glance to succeed one another in pretty regular bands, careful examination shows that in certain places the augen- gneiss cuts across the other bands, as shown in the figure, the foliation in the transverse arm running parallel to the regular foliation and banding of the whole exposure, but not coinciding witli the direction of the arm it.self. In the thinner apophyses the granulation is more advanced and the augen less abundant than in the heavier bands from which it proceinls. Figurt' ."i. Dyke of I'cgnmtito cniHlifd to Augeii-(!ni'iss, tlic foliation of which coin- fides witli that of the Anorthositp through which it cuts. (Range VIII., Lot It), Township of Hrandon.) Figure 5 shows a similar case where a pegmatite ilyke crushed to an augen-gneiss cuts obliquely across the foliation of the anorthosite in the township of Hrandon. 'if X .'I f.vU 4l> j gUKIIKC. It is thus evident that in these cases, and jirobal»ly in the c';ise.s of all the uuj,'en-gneisses, we liave to do with granitic intrusions into earlier rocks, which intrusions certainly date from a time before the development of the foliation of the gneisses, or at lea.>*t before the foliating forces had ceased to act. Treiiililin^f .Miiiiiitiiiii Structure. (Jraimlated Gneina (Qnartx-Ortlioi-lituc-Hurnhh inh-UmiHs) — 7'rei)ib/!ii;/ Mountain, Tdiciinhip of Joly (Sections ''t2S, 't,iO, .'t.iS, o-iJf). This mountain, which, as is well known, is the highest j)oint in the whole Laurentian range of this part of Canada, rises 23H0 feet above sea-lev^! and 1720 feet alK)ve the waters of Trembling Lake, which lie aloig its foot. (Plate TI.) It is sculptured out of a great mass of gneiss, uniform in character from base to summit, and has an e.special iiiterest in that it was cited by Sir William I^ogan as the typical occurrence of the Fundamental Gneiss, which he Iwlieved to lie at the base of the whole Laurentian system. This gneiss is rather tine in grain, !ind has a di.stinct though not very striking foliation, marked by the presence of a series of thin, interrupted black lines, seen on surfaces broken at right angles to the foliation. On large weathered surfaces a slight variation in size of grain can occasionally be seen in thin bands parallel to the foliation, and at long intervals, thin bands of a black pyroxenic ampliibolite are met with. The gneiss has a pale reddish colour when fresh, and weatheis brownish-gray. Under the microscope it is seen to be composed essentially of ortho- clase, quartz and hornblende, the tirst-mentioned mineml preponder- ating largely. As accessary constituents, magnetite, pioi)ably con- taining a certain amount of titanium as in one case it was observed associated with a substance resembling leucoxene, and in .some slides a few grains of plagioclase and biotite, are found. A few little zircons and a few irregular grains of a mineral probably apatite are always present, and in one of the specimens a not inconsiderable quantity of a rhombic pyroxene was associated with the hornblende in little irregular grain.s, without however affording any evidence of having been derived from this latter mineral. The structure of the rock is remarkable. (Plate IV., Fig. 1.) No more typical 'jxample of a cataclastic or " mortel " .structure could be found. Large, very irregular-shaped, often more or less rounded indivi- duals of orthoclase, presenting a fibrous appearance, due to a very fine, microperthitic iutergrowth and showing excellent strain-shodow.s, lie I the ciises of jtrusif)us into I, tiiiit! before last before the ct though not aeries of thin, it angles to the ation ill size of )o the foliation, ainpliil)olite are len tresli, and itially of ortho- eml ineponcler- prolmbly con- it was observed in some slides a BW little zircons itite are always blc quantity of ilende in little lence of having ^•., Fig. 1.) ^o ructure could he i rounded indivi- le to a very fine, •ain-shadows, lie (iKOLOOICAr. SlHVRV OK CaNAI)'. Vol. vim., I'aut J. Fkj. 1. Flo. 2. Fid. .S. Fid. 4. PLATE IV. Fid. 1. -"FtNI)AMKNTAI,(iNKmM,"TllKJIIll.lNii MOUNTAIN HoillliloiKli', DrtlloclllHO luul Quait/.. X 10. Fid. 2. Lkaf (iNRiss, 34 MILKS NOHTH-KAsT OK St. .T(::itAME— OrtluKjIase and (Quartz. X 10. Fig. 3.-~(iAKNKTIKKHOLS SlLLI.MANITK-GNKlS,S, 1 MILK WKST OK ST. JkAN 1)E MATHA-Oariiet, Silli- nmnite, <.|Juartz, Orthoclase and Pyrite. X 10. Flu. 4.— SlLLlMANITE CllYSTALS IN (JNRISS KHOM WKST SHORE OK TUKMBLINO LaKK. II : t\ 'P^ k il If n ! , I f f ] PETHOGKAPHY OF THE LAURENTIAN. 43 J imbedded in a very tinely granulated mass, making up the {greater part of the rock, composed also of ortlioclase, and which can be plainly seen to have been derived from the breaking down of the larger ortho- clases, the process being actually ol served in all its stages in the sections. The process consists partly in peripheral granulation and partly in the subdivision of the larger individuals into smaller ones, by the develop- ment of lines of this broken material across them in tlie direction of greatest stress. The quartz, the larger individuals of which frequently contain little rows of the minute dark inclusions often seen in the quartz of granite, though present in smaller amount, presents the same phenomena. This is also true of the hprnblende, the large individuals of which are for the most part broken into fragments which are arranged in rudely parallel lines, forming the interrupted black lines above mentioned as marking the foliation of the rock. The origin of the gneissic structure in the case of this rock admits of no question. It is not an original structure, nor a survival of bedding indicating a sedi- mentary origin, but it has been produced by movements in the lock brought about by crushing, the original rock having been a hornblende- granite. In order to ascertain whether the chemical composition of this rock ciumiicnl would bear out the conclusions derived from its study in the field '■'""'l'"'" '""• and under tlie microscope, an analysis of it was made for me by Mr. Walter C. Adams, B.A.Sc. The results of this analysis are given below under I., while under II. the results of the analysis of a granite from the Carlingford District, in Ireland, by Haughton, aie presented for pui'poses of comparison :— I. IT. Silica Alumina Ferric oxide . ... .Maii^unuus uxidc Linii' MogneHia Soda PutiUiua LoHB on ignition . . Total alkalieH . (iNKISS. (iH.\SITK. Trt'iiibliiix Mt. Curliugford Wl 24 . 70 4« 1485 14 24 2«2 3 72 45 2 10 1 48 ■S»7 40 4-30 3'))6 4 33 4 2(5 70 1 .')!• !t!l 5« !I!IS3 8 ({3 7 02 'if The composition is that of a typical granite, and is entirely diil'erent from that of the gneisses of Class II., of which the analyses are discussed ^'• r^' 44 J QUEBEC. on pages 59 J to 61 J. The points of distinction, and those which mark it as of igneous origin, are high silica combined with low alumina, and high percentage of alkalies. The lime also, as is usually the case in granites, is in excess of the magnesia. For a description of the bands or stratiform masses of pyroxene- amphibolite which are intercalated in tliis gneiss, see page 77 .r. Leaf-Gneiss— (Quartz-Orthorlam'-G miss) — 3i mihs North-east of St. J&otne (Sections 334, '^05). Leaf giu'isH. As a typical locality for this important and interesting variety of gneiss, certain large exposures protruding througli the drift near the southern edge of the protaxis, and alx)ut 3i miles from St. J^r6me, by the side of the Great Northern Railway between this place and New Glasgow, may be taken. The rock is pink in colour, fine in grain, excellently foliated, and practically free from all iron-magnesia constituents. In the hand specimen it appears to consist of veiy thin alternate layei-s of quartz and orthoclase. The quartz, however, can scarcely be said to occur in layers, but rather in long narrow leaves, presenting the appearance of layers, when the specimen is broken at right angles to the foliation in one direction, but appearing as much shorter layers or dashes when the rock is broken in the other direction, at right angles to the foliation. When, on the other hand, the rock is broken in a direction parallel to the foliat.'on, the quartz presents the appearance of having been smeared over th 3 felspar surface, in long, narrow sti'eaks, very much as butter might be thinly spread on bread. ' Under the microscope, in a section cut at right angles to the foliation the rock (Plate IV., Fig. 2) is seen to be compo.sed of a uniform mosaic of felspar grains, through which the quartz runs in nar- row, sharply defined bands. These quartz hands in polarized light resolve themselves into a series of individuals, each having a long rectangular section, and placed end to end, the bands being remarkal)ly Stmetuie. uniform in width and sharply defined against the felspar mosaic on either side. The quartz individuals are sometimes as much as ten times as long as they are wide, and yet have an almost absolutely <*ven extinction. The orthoclase which constitutes the greater part of the >k rock, forms, as has been mentioned, a mosaic of much smaller grains, showing, as a general rule, l)etween crossed nicols the wavy lines, due to fine microperthitic intergrowths, so often seen in gneisses. These grains fit into one another along very serrated boundaries ; they do •] PETRO(}RAPHY OF THE LAURENTIAN. 45 J which mark lumina, and the case in f pyroxene- 77.1. east of St. g variety of ift near the J^r6me, by ce and New oliated, and n the hand rs of quartz i to occur in ppearance of bhe foliation dashes when igles to the n a direction ice of having st!"eaks, very the foliation jf a uniform runs in nar- »lari/ed light wing a long g remarkably ar mosaic on much as ten >solutely even r part of the nailer grains, ivy lines, due lisses. These ries ; they do f til I' K'l.'iss. not show any very pronounced strain-shadows, neither are there any augen or remnants of larger grains to be seen. Smaller and larger grains are present, but there is no distinct evidence of the larger breaking up into the smaller. A grain or two of plagiodase is seen in each slide, as well as one or two very small decomposed remnants of what may have originally been minute mica scales. The structure suggests a completely granulated rock, in which the fomplctf granulation has, perhaps, been effected in part, at least, by re-crystal- li/ation. Gneisses presenting this Ir f structure with its accompanying micro- DiHtrilintiiu scopic characters are abundant and occur in many widely separated " parts of the area embraced in this report. They are for instance, very extensively developed in the last range of the township of Cartieri being excellently exposured on the shores and islands of the typical little Laurontian lakes wiiich lie between the two branches of the er L'Assomption, one of which runs out of Lac des Ilets, and the •■ lier out of Lake L'Assomption. Several of these lakes are rock-basins which have been excavated out of this gneiss. The gneiss from this locality (section 348), closely resembles that above described, although tiie (|uartz leaves are not so sharp and regular, and plagiodase, in clear, brightly polarizing grains, is more abundant. There are also a number of little scales of biotite scatteied through the rock as well as a few very small isotropic red garnets. As before, the appearance under the microscope is suggestive of granulation with at least partial ro-crystallization, altliougli no absolute proof of this can be obtained. At many places in the township of Brandon also leaf-gneiss occurs inlerbanded with j)yroxetiu-granulito, (|uartzite, &v., consisting as before of (juartz and orthoclase, iron-magnesia constituents being absent or represented by a few grains of iron ore. One of these localities is lot 13 of range VI. (section 685), by the side of the road which crosses this lot, where the gneiss is interbanded with pyroxene- graiiulite and often t^ut by irregular shaped masses of augen-gneiss, running now with and now across the direction of foliation as above desci'ibed. , On lots 18 of range V. and 15 of range IX. (section 57G), of the same township, this same variety of gneiss is also well expo.sed, the latter locality being at the westerly contact of the most eastwardly of the anorthosite masses which occur in this township. In the very fine- grained felspar groundmass of these rocks, however, occasional larger grains of orthoclase can be seen which are much twisted, show a very uneven extinction, and can in some cases be seen to be undergoing a J'-' .1 I • ' I;; . i! ,1! :/ 46 J QUEUKC. 1 I:. li m Hi :'l! TranHitioiial forms. Tlie structure of inccliaiiical origin. process of periplienil granulation, giving riSe to smaller grains like tho.se of the groundmass. In the rock from the latter locality also, sections show distinctly that a movement in the direction of the foliation has taken place in the felspar mosaic, during or subsequent to its formation. I'ransitional Forinn. Between augen-gneiss and leaf-gneiss all po.ssible intermediate varietie^ are found in various parts of the area. Such inteimediate forms present leaves or thin layers of quartz alternating with layers of finely granular orthoclase, in which the augen or remnants of large orthoclaso individuals are more or less abundant. When these augen are large and abundant the rock approaches an augen-gneiss on one hand ; when the granulating process has so fa;- advanced that they have become greatly reduced in number and size, or have almost disappeared, the rock passes gradually over into a leaf-gneiss on the other, (ineisses are often found which would l)e classed as leaf- gneiss but which on careful examination show a few minute twisted remnants of orthoclase augen, here and there, indicating the true character of the i-ock. The great granite mass occupying the eastern side of the township of Brandon, along its northern limits assumes first the form of an augen- gneiss, and then passes over into such a leaf-gnei.ss (section 660), m Inch, however, is poor in quartz, the transition being excellently seen on the shores of Lake Sacacomie, which lies just beyond the eastern limits of the map. Many similar cases of pegmatites passing into augen- gneiss and then into leaf-gneiss have been observed, and even when the tiansition cannot be seen, transitional forms are so common as to render the conclusion inevitable that many at least if not all the typical leaf-gneisses have been derived from the crushing or foliation of coarse granite rocks, having passed through the intermediate stage of augen- gneiss. In a similar manner those forms of leaf-gneiss in which the quartz individuals are smaller, occurring in the form of little dashes or scales rather than leaves, have probably been formed from finer graineil rocks of similar character, passing through an "intermediate stage such as that described in the Trembling Mountain gneiss, which, after all, is a species of microscopic augen-gneiss. In the movements which have taken place in these rocks, resulting in the development of a foliated structure, the processes at work are, it is believed, chiefly mechanical. In certain districts which have been made the subjects of careful study elsewhere, structures resembling closely those above described 1|/-;; ! ADAM*. 1 PETROGHAHHY OK TIIK LAUKENTIAX. 47 J lins like those also, sections foliation has its formation. intermediate intermediate ig with layers nants of large n these aiifj;en i»neias on one ced that they • luive almost ■aneiss on the lassed as leaf- ninute twisted iting the true he township of n of an augen- jn 660), which, tly seen on the eastern limits ing into augen- and even when I common as to t all the typical iation of coarse itage of augen- s in which the little dashes or •m finer graineil liate stage such vhich, after all, (vements which velopment of a jelieved, chiefly Ejects of careful above described have been thought to have been produced by i he breaking down and re-crystallization of the original constituents. This does not seem to be true in these Laurentian gneisses — for in the case of the felspar and hornblende the granulated material is exactly th*^ same to all appearances as the larger augen. Even when the latter consist of microperthite the granulated material hiis also the same character, which would hardly be expected if a re-crystallization had taken place. Sericite and the various other minerals so often produced during the re-crystallization of rocks under the influence of pressure are also absent. The effect of the pressure on the quartz is especially remarkable, for, as has been stated, the indi\in Orossai^hHen u. tl. C^uartziihorphyrt' von Thai ill) Thiiiiiittt'ii. (Iiiaug IMhh. Hfigie &c. This gneiss occurs in thick bands, interstratified with and overlain by st. .Fean dc the white garnetiferous quartzite described on page 62 j, the whole '• lying very nearly horizontal. The gneiss weathei-s exceedingly rusty, but on the fresh surface is seen to be tine in grain and dark-gray in colour, small garnets and graphite scales being readily recognized in it. It is more uniform in character than is usual in gneisses, the strike 50 J yUKBEr;. Sillinuiiiiti Pyiite iiiid grapliite. being marked by bands somewhat richer or poorer in garnet, or >)y other slight differences in composition. Under the microscope the rock is seen to consist of garnet, sillimanite and (|uartz in large amount, with some ortlioclase and iron pyrite, and a little biotite, rutile and graphite. (Plate IV., Fig. 3.) The garnet individuals, which are usually large, are more or less rounded in form, but frequently elongated in the direction of the foliation, and, as is usually the case in these Laurentian gneisses, are perfectly isotropic. They frequently hold inclusions of (|uartz, silli- manite and rutile, and pre.sent the appearance of having grown in the rock and inclosed these other older constituents. The sillimanite occurs in colourless elongated prisms from 'Ot) to "'ir' millimetres in diameter, the longest individuals being somewhat over 1"1 millimetres in length, and often slightly curved, apparently by pressure. It has a rather high index of refractinVi, as well as a rather liigh double refraction. The longitudinal sections show the cleavage parallel to the macropinacoid as a series of fine lines parallel to the longer axis, except when cut parallel to this face. They also show the transverse cracks usually seen in long and slender prisms. When tested by means of the quartz wedge it is found that c= C. Terminal faces cannot be recognized. In transverse sections the prisms are seen to have the nearly square cross section of the prism ooPii. The cleav- age crosses these sections diagonally, and in the directicm of this cleavage lies the plane of the optic axe.^, the axial angle being small. These properties serve to identify the mineral and to distinguish it from wollastonite or andalusite, which in certain respects it resembles. (Plate IV., Fig. 4.) The quartz, which is uniaxial and positive, contains, as is very frequently the case in these gneisses, many minute straight hair-like inclusions, which are dark in colour. In the great majority of cases, it shows a more or less pronounced uneven extinction, and the grains are often long and narrow, the longer axes lying in the direction of the foliation. The orthoclase possesses the usual characters, and between crossed nicols sonietimes has the faintly fibrous appearance often seen in the orthoclase of gneisses, the larger grains showing strain-shadows jus in the case of the quartz. The biotite occurs in very small amount, and in small individuals of a deep brown colour, here and there slightly twisted. The rutile appears as a few irregular-shaped, nearly opaque, little grains. The pyrite, the presence of which gives rise to •J PETKOGKAPHY OF TIIK LAUKKNTIAN, 51 .1 4; i irnet, or by b, sillimanite I pyrite, and more or less iction of the gneisses, are (juartz, silli- Tiown in the oin -05 to -if' (inewhat over pparently by bU as a rather V the cleavage urallel to tlie also show the risms. When : C. Terminal )risnis are seen The cleav- •efti«)n of this le being small, distinguish it ts it resembles. tins, as is very ■aight hair-like ijority of cases, and the grains the direction of jetween crossed 'ten seen in the ii-shadows as in all amount, and there slightly , nearly opaque, 1 gives rise to the rusty weathering of the rock, and which occurs in considerable amount, is in the form of little irregular-shaped strings and masses scattered through the rock. It frequently occupies little cracks r.inning tlirough the various other minerah or surrounding them. It sometimes occurs well crystallized, but is often very Hne-grained and in little masses liaving a concentric banded structure like th t seen in agate, the mineral having evidently been deposited in little cavities sub- sequent to the crystallization of the rock and being frequently related to the graphite in such a way as to suggest that the pyi-ite had been deposited owing to a reducing action on the part of tlie carbon. The graphite, which in the hand specimens seems to be somewhat abun- dant, is seen in the thin sections to occur in the form of small elongated individuals, black and quite opa(]UC. A study of the thin sections also shows the rock to be quite dill'er- ent from the (|uartz-orthoclase-gneis.ses already described, not only in mineralogical composition but also in structure. The elongated individuals of sillimanite, quartz, etc., lying in one direction, mark the foliation of the rock, though this is not very pronounced. No evidence of granulation, however, is to be seen, the pressure Nn ividencc which granulated the gneisses of the last class, having, to all appear- tjon!'"'" ' ances, crystallized these /;* nitit, the constituents being, in the nomen- clature of Milch, "eleutheromorphic."* The uneven extinction of the sillimanite, (|uartz, and orthoolase would, however, seem to indicate that the rock had been subjected to .some pressure since their development : but on the other hand, the garnet, which was developed later being (juite isotropic, would seem to have been produced during the linal compression of the rock. Another locality at which a gneiss almost identical in character occurs «liiiiiet. is in the front of lot 4 of range X. of the township of Brandon. (Section 080). Where the load crosses this lot there are large exposures of gneiss consisting of an alternation of small bands of augen-gneiss and loaf-gneiss holding little augen, with other rocks of the nature of amphibolite or pyroxene-granulites often holding quartz ; as well as with a few bands of this rusty garnetiferous sillimanite-gneiss and some calcareous gneiss or very impure limestone. Both the augen- gneiss and tlie amphil)olite-gneiss occasionally hold garnet". The rusty-weathering gneiss is seen under the microscope to be composed essentially of garnet, sillimanite, orthoclase and quartz, with pyrite, lutile and biotite in very subordinate amount. The garnet, as before, * Hciti'iige xur Lehre von dor Regionahnetanioriihose— Neue» Jahrbuoh ftir NFiiuTnlogif, IX Hi'ilaKt' Hand. S. 10". H r.\ ii li^ll 1 i-; i wu 1 ':■ :*r\\ : ■!.■ ■ m '4 : X ill 52 J QUEBEC. is in the form of irregular-slmped masses, having a sponge-like char- acter owing to the numerous inclusions of biotite, felspar, sillimanite ami rutile which it contains, it is as in the rock last described quite isotropic. The pyrite occurs tilling little cracks and was apparently infiltrated after the crystallization of the rock. No graphite is to be seen in the specimen or slide. This rock, like that from near St. Jean de Matha, shows no evidence of cataclastic structure, but has apparently resulted from an entire re-crystallization in situ under pressure. Tho same is true of the quartzose garnetiferous gneiss inter, .mnded with this rusty gneiss. Tiiere can be no doubt in the case of these exposures, that the augen- gneiss and the leaf-gneiss produced from it, are of igneous origin. Two othei" occurrences of this peculiar rusty-weathering gneiss may also be referred to ; in these, howevei', the orthoclase has a granulated appeaiance, although no absolute proof of its cataclastic origin can be obtained. Gam etiferoiii* Sillinin n ife- (I'neinx — Hoail l>et irei- ii thfToic nsfiip of Kifda re and Lake Rocher — tieignior)/ of D'Aryeiiteiiil. (Section 30^.) Kildaie. At this locality there are a series of exposures representing a very consideiable thickness of strata made up of an alternation of grayish quartzose gnei.ss, with thick bands of white gainetiferous quartzite and of this rusty-weuthering gneiss. There is also in one place a band of white crystalline limestone, holding grains of dark-green serpentine. This is exposed for a width of twenty feet, and occurs interstratified be- tween a band of white quartzite and one of the rusty gneiss. Ail these rocks frequently hold a little graphite. The rusty-weathering gneiss as before consists of garnet, orthoclase, quartz and sillimanite with pyrite and a little rutile and graphite. The contrast between the ver}' rusty weathered surface of this gneiss and the pale-gray almost white colour of its surface on a fresh fracture is very striking. Garnetiferous Sillimanite-Gneiitu — Toinmhip of KiJdare, near tlie line between Ram/es XI. and XII. (Section ^30.) This locality is just to the west of Lake Fran<;ais, and on a con- tinuation of the same section as that in which the last-mentioned rock occurs, but about three miles further west. It is the first exposure on •] PETROfilMI'llY OK THE LAUKENTIAN. 53 J ;e-like char- r, sillimanite scribed quite IS apparently lite is to be "om near St. ructure, but in situ under < gneisH inter. mt the augen- 8 origin. ng gnei.ss may 1 a granulated origin can be xhipof KilduiH Hon 30 J.) ;enting a very ion of grayish s quartzite and )lace a band of Ben serpentine, ^rstratitied be- eiss. All these lering gneiss as lite with pyrite the very rusty st white colour ?, near the fine 0.) i, and on a con- mentioned rock irst exposure on the road, to the west of the anorthosite band which passes under the lake. The rock consists essentially of garnet, sillimanite, quartz and orthoclase, the garnet often inclosing the sillimanite. It is almost identical in character with the rusty-weathering gneiss of the other localities described above. As examples of the second set of these rocks before mentioned, which, while very similar to those just described, do not contain pyrite, and consecjuently are not distinguished in tlie field by the rusty sand-like disintegration product, the following may be selected : — (ianmtiferons Sillinianiti'Gniixn — ,i mill's north-irist of St. Jt'cm i/e Maiha — Seigiiinri/ <>f De Ramsatj. (iSection 563.) This rock occurs three miles in a straight line north-west of St. Nortli-west of Jean de Matha, at the bridge where the road from this place to Ste. Matlnv. Emilie crosses the Black River. The gneisses here lie practically horizontal. The rock is red in colour, and highly garnetiferous. Under the microscope the rock is seen to be composed of garnet, • sillimanite, quartz and orthoclase, with smaller amounts of rutile, serpentine, pyrite, graphite and biotite. The general characters of these minerals are tlie same as those which they present in the rocks of the last set just described. The garnet is perfectly isotropic. The sillimanite is present in considerable amount, in prisms whose long axes lie parallel to the foliation of t|je rock. The (juartz contains a great abundance of minute, black, hair-like inclusions, quite straight and arranged in several intersecting' series. The orthoclase has a distinctly fibrous appearance, owing, in part at least, to the presence of little, rod-like inclusions, some black and nearly opa()ue, others transparent and nearly colourless. The rutile is present in deep brown, nearly opaque grains, sometimes having a tolerably good prismatic form, but gener- ally more or less rounded. The serpentine occurs in a few large grains derived from the alteration of some mineral, which has now entirely disappeared. Giaphite is scattered through the rock in numerous little iiakes. The biotite occurs in very small amount, often inclosed in the garnet. Only a very few small grains of pyrite are present. The rock, as has been stated, is very highly garnetiferous, the garnet occurring in lumps of a pink colour, making up a large ;■ lii- nil IVt]' H' h s* 54 .1 (jUEnst'. part of tlie rock, the other conptituents of the rock being much more fine in grain luul Wowing round the hirge garnet lumps, thus giving rise to an indistinct foliation in the direction of the motion. The structure, however, is <|uite different from that of augen- or leaf- gneiss, for the study of the thin sections affords no indication of granulation. The large garnet lumps crystallized in nifii and are uncrushed. They are not remnants of larger masses which have escaped complete granulation. The sillimanito appears to be some- what broken is places, but this is not certain, and a study of the thin sections proves that at least some, if not all, the constituents of the lock have been produced by a process of re-crystallization. SUf!iiianili;-(i'nelsK. — West shore of Ih'eiiihUng Lake. (Section •'>!>/.) Trembliiitr Luke giipiHs ■'Hi' i The geology of Trembling Lake, which large sheet of water lies near the north-west corner of the accompanying map, is of especial interest. Along the eastern shore of the lake rises Trembling Mountain, the highest point in this part of the Dominion, and which, as already state* aeieulni- crystuls (Plate IV., Fig. 4) and, having a rudely parallel direction, give to the rock, which is otherwise niaM.sive, an indistinctly foliated appearance. Kigurf (i. ,SilliiiiiiiiiU'-f Tn'iubling Liiki'. Sillinmiiitf, <^iiai-t/., OrthooliiKH, Hiotit*- and I'yrite. x 38. The accompanying figure (No. 6) shows the appearance of the rock under the niicrosoope, portions of two Ijands rich in silliinanite with an intervening band rich in biotito being shown. As accessary constitu- ents present in small amount, the rock contains garnet, titaniferous iron ore, a few grains of pyrite and of a mineral which has the characters of allanite, pleochioic in pale brownish and ^^reen tints and deeper in colour in the interior of the grain. These constituents are bounded by well defined, sharp lines ; there is no granulation, and no twisting of the grains. The rock has the appearance of having been entirely re- crystalli/ed, and resembles certain altered rocks found in the contact zones al»out great granite masses. It bears as strong a resemblance to a metamorphosed sediment on Ri'^tiiil'liwce 11 1 1 I.' 'II 1 !• Ai ■ 1 • to altcri'd one hand as the rock ot I remnluig i\lountam does to an igneous mass HediiiKiitary on the other — resemblances which in each case are emphasized by the ''"^'^'^*'- chemical composition of the rock. Garnet iferoHs Silliinanlti'-Gneitn. — Daririn's Falls on Biver Ouareaii, near Village of Hairdon, I'oivnship of Raudon. (Sections 637, 638.) At Darwin's Falls, which are about a quarter of a mile below the lower bridge at Rawdon, the river cuts its way through a gorge of Laurentian rocks which are well banded and dip to the west at a high ii| ■ i ■ > 56 J yUKHEC. angle, tlie attitude being nearly vertical. The gneiss is in most places highly garnetit'erous, the pink garnets occurring in lumps sometimes as much as an inch in diameter, and is interstratified with bands of white quartzite (described on page 62 j), some of which are highly garnetifer- ous, while others are nearly free from garnet. There are also bands of felspathic quartzite. The bands of these various rocks, which have all the appedvance of beds, are from a few inches to several feet in thickness. Diiiwins Falls Tn one place a little String of crystalline limestone about ;-ri inch wide was found, but no larger band could be discovered : to the north, however, nearly on the strike of the.se exposures, a heavy band of crystal- line limestone appears, which may possibly cro.ss the river just above the village, where the banks are heavily drift-covered. This locality has already been referred to in describing the distribution of the lime- stone bands on page 2") .(. The microscopic character of the quartzite interbanded with the gneiss, is described on page 62 J. The gneiss contains much garnet and sillimanite, but differs from t!ie gneis.ses of the class before described, in that it is much more highly quartzose. The garnet occurs in numerous irregular-shaped grains with the peculiar arm-like extensions running out into the web of the rock in all directions and inclosing individuals of the other constituents. Ortho- clase, quartz, sillimanite, biotite, rutile and iron ore have been observed thus inclosed in the garnet, so that the latter mineral would appear to < ;,!! Figure 7.- (Jarnct holding' iiiclnHioiis of (itlitT (.■(iiistitiu'iits of tlw rock ■(larnt'tiftTor.s Silliiiiiiiiit<'-(iiiiiKH^r)arwiirN FhUh, iifiir KiivmIom. Ganxt witli '^"^^'^ '"'^" developed later than any of the other constituents of the iiurluHioiis. pock. This peculiar mode of growth on the part of the garnet is seen almost invariably in the garnetiferous gneiss of the Laurentian, as well as in the highly altered sedimentary strata folded into the Alps ADAMS. 1 PETROGRAPHY OP THE LAURESTIAN. 57 'f ' ': f lost places netimes as la of white garnetifer- io bands of 3h have all ■al feet in jt rn inch the north, 1 of crystal- just above his locality Df the limc- le quartzite ;rs from t!ie Qore highly IS with the e rock in all its. Ortho- len oV)served Id appear to (liiiiH'tifti-ous lents of the ;arnet is seen itian, as well to the Alps (Bundner Schiefer) and elsewhere, and has already been noted as occurring in some of the rocks described above. The mineral appears to add to its substance in all directions in which material which will yield garnet can be reached, and even seems to be assimilating or in some way getting rid of grains of the most diverse minerals which it has inclosed, minute irregularly rounded remnants of many of these alone remaining in the interior of the garnet individuals, while the peripheral portions are often still full of inclusion^-. How this is accomplished it must be left for future investigation to decide, for, in the manner in which these garnets and other minerals developed by nietamorphic processes grow in solid rocks, there is much which is as yet mysterious and not by any means thoroughly undei-stood. The garnet filled with inclusions, in its want of continuity often resembles a sponge, or a great AnKvba whose substance is barely sufficient to inclose the miscellaneous collections of objects on which it is feeding. In addition to the garnets and (juartz, orthoclase and sillinianite are abundant, while biolite, rutile, iron ore, pyrite, and zircon(?) are present in small amount, all these minerals presenting the normal characters (jf the several species. The rock has an indistinct foliation, due in part to the arrangement of the various minerals with their longer axes in one plane, and in part to a certain variation in relative abundance of the different minerals in diflerent planes. The quartz and orthoclase show ell'ects of pressure, but no undoubted granulation or distant cataclastic structure is seen in the slides, neither are there any augen. The garnet and siliimanite are certainly due to re crystallization, and the evidence goes to show that the rock as a whole has resulted from this process. It has, however, since le-crystallization, been subjected to a certain amount of pre.ssure, for although in some cases the quartz and orthoclase show slight evidences of pressure this has not affected the garnet at all. Chemical Compus'Uion of Ihn Gneisses of Class II. In order to ascertain whether the gneisses of Class II., which differ chemical so distinctly in mineralcgical composition and structure from those ^"".•|,'",'^^^^^^^^^ of Cl.iss I., present differences in the chemical composition of the rock Class II. as a whole, three of the most typical gneisses of the class were selected from those described and were analyzed. The results of these analyses are given below. No. III. was made for me by Mr. Nevil Norton Evans, of McGill University, and Nos. IV. and VII. by Mrs. :l i. ♦«.■• '■iifl '1-i il !.;■> m m m Different in eiiiii|i()Hiti(iii from liny iffneouH rf)ck. 58 J QUEBEC. Walter C. Adams, B.A.Sc. To both gentlemen I desire to acknow- ledge my great indebtedness. ', -, III. (JXKISS. St. .lean de M. IV. (iNKIS«. Trembling I^ake. V. Sl.ATK. Walet.. VI. Slatk. Mel- lxj\iriie. 04 20 VII. 3 FerriJiiH oxide Ferric milpliide .Manganous oxide Lime Magnefiia . . Sf)da 4 CO 4 33 trace. 35 1-81 ■70 2-50 1-82* 1 (4 trace. lie 3 50 m 5 72 1-50 783 4 23 trace. 1 12 2 20 2 at 3 18 3 .30 • • ■ • l^.,- 3 94 3-07 3 20 3 42 99 05 0.3 Vt 1 07 1-87 4-.> 95 I 05 99 08 1 37 ■"■70' 152 04 Po«T.SMa _ 2 30 Total alkalies !«f55 3 at 10(t 77 C 32 100 03 5.38 100 44 2 94 • Water. III. (Jneiss from aljoiit one mile west of St. .lean de Matlia. \ tine-grainwl garnetiferouH sillimaiiite-gneisw, containing mncli quart/, and ortlioelase. • rraphite and pyrite are also present, the latter causing the gneiss to weather to a very rusty colour. Ft occurs in thick hands interstratitied with white garnetiferous (|uart/,ite, the whole lying nearly flat. (See page 49 .l\. IV. (ineiss from the west shore of Trembling Lake. A finegrained dark gray gneiss, comiM)sed of ({uarty. and ortlioelase, with nnich hiotite and silli- manite. It r(.iie* acknow- viu. 8S. Sl.ATK. Dii.jTiiizeii. « 8 02 Ii4 (> (i8 JO )7 7C. S7 1 52 4J •(i4 !ir, 2 30 05 08 100 44 37 2 'J4 fint'-Ki'aiiifd iii'thocliist'. IS to Wfiithf r il with whit*' (1 (lurk griiy iti' iiiid silli- c)t'cti|ii»'s tlic itcrry Hunt. ill tilt' Town- 3 of (^ll('l)f('. ).) iiicf (if .0. liiif, Switmi- lai'ti!. (V'diii ree gneisses tnin gneiss, (imposition. ,i»y igneous in III. and ] PETROGRAPHY OF THF, ; \URBNTIAN. 59 J IV.), the low percentage of alkalies', hi7 ' 85 Alumina IT'S" !M0 Ferrous oxidt' 007 1114 ManganouH oxide 70 '7!* Lime 114 98 Mapfnesia 581 .3-23 Soda 112 1-80 Potassft 2!»7 '44 Loss on ignition 526 455 iKCfill IK) -88 Total alkalies 409 224 The amount of carbon present was determined in No. TX. and found to be "26 per cent ; all the iron was found to be present in the ferrous state. These two slates, as will be seen, contain the proper relative •] PKTKOGKAPHY OF THE LAURENTIAN. 61 J proportion of constituents for the formation of gneisses like those just described. No. IX. might, if submitted to the proper conditions for its metamorphosis, produce a gneiss similar, in a general way, to that from Tiembling Lake, but poorer in sillimanite, while No. X. would crystallize into a gneiss like that from Darwin's Falls (No. VII.), but less quartzose. In these gneisses which have been classed as of sedimentary origin, we have therefore rocks which have the chemical composition of shales or slates, a minerulogical composition quite different from that of the gneisses of Class I., and a structure which shows that they have been produced essentially by a process of re-crystallization. These facts, it is believed, taken together, establish the right of these rocks to be considered as altered sediments. The efJects produced by the dynamic metamorphism are along the same lines as those observed by Heim in the Alps, the same force which crushes tiie highly crystalline rocks into finely granular schists, re-crystallizes the sedimentary rocks, often developing large individuals of various new minerals in them. It is not, however, claimed that all granulated rocks in the Lauren- n • • ■ I II 11. 1 • 1. 1 All graini- tian are or igneous origin or that all re-crystallized gneisses are altered lated rocks sediments.* If any arkoses or coarse felspathic sandstones were ""' igm'ous. deposited with the shales, those being very similar to granite in character would probably be altered by crushing and granulation to gneisses almost identical in appearance, and under the microscope with those prcxluced from granites ; futlier study may indeed show this to be the origin of some of the quartzose orthoclase-gneisses associated with the garnetiferous sillimanite-gneisses aliove described. It is also pos- sible that certain igneous rocks have undergone a complete re-crys- tallization during metamorphism. It is desired in the present con- tribution to our knowledge of these rocks merely to show that certain of these gneisses have had a sedimentaiy origin, and that certain others can be recognized as altered igneous rocks, while very many stili remain whose origin is, as yet, undetermined. Distinct from the little strings and veins of quartz which are often Qimrtzites. found cutting the rocks of this as of all other great districts of crys- talline strata, are the well defined and often very ihick bands of quartz- ite which occur regularly interbanded or interstratified with the gneiss and crystalline limestones of the district. Of these the following thriee occurrences may be selected as typical : — •See C. J. Smyth, .Ir., Metamor]>hiHm of a CJabbro occurring in St. Lawrence County, N.Y. Am. Jour. Sci., April, 1896, p. 280. M% ^ 'i: f \k ^ii'rt 62 J VUEHKC. CTarnctifeiDiir qumtzitf. St. .Tf-aii fU- Matliii. Garnetifcroua Quartzite — About onp mile toeat of the Church of St. Jean de Matha, Seigniory of De Rammif. (Sections o7S, (U>1 ). This rock occurs interstnititied with and oveilying the garnetiferous silliinanite-gneiss desci-ibed on page 49 J, ff)rming great exposures extending ofl" to the north-west. One great cliflF of these rocks, inter- stratified with garnetiferous quartzose gnei.ss, is represented in the photograph reproduced in Plate III. The beds, as will be seen in the photograph, are pi-actically horizontal. The quartzite is of medium grain and brownish-gray colour, and holds numerous garnets, often as much as an inch in diameter, liands richer or poorer in garnet or showing other slight differences in char- acter alternate with one another. Under the microscope the rock is .seen to consist essentially of quartz and garnet. Silliinanite is present in considerable amount with accessary orthoelase, plagioclase, biotite, and rutile. The indistinct foliation of the rock is caused by the arrangement of the various constituents with their long axes in one direction. The quartz consists of larger grains with streams of little ones run- ning between them, almost and only a 'ring in the Of these t fiequently fine-grained into masses ?, or else are Paces. Con- i on some of early white [)ther parts ving to the n. jding uue to le accessary usually asso- arnetiferous argillaceous of this area, nicroscopical ReiHirt of tilt! •al MiHU)ry for They Serjx'iitine ivltfred Cry»tnlline Limestone — Township of Rarvdon, Range X., Lota 21 and 28 (near lime-kiln) — (Sections 6S2, fiJO). These exposures are among the largest in the whole area and have Knwdon already been referred to on page 27 J. The rock is well banded, some bands consisting of a white and almost pure limestone containing only a few scales of mica, while other bands are filled with grains of dark- green serpentine. In some of these serpentinous bands the serpentine is present in the form of large lumps, and on breaking open a nunil)er of these some were found to contain rounded cores of white pyroxene. The.se cores are readily detached from the inclosing serpentine by the tap of a hammer and fall out leaving hemispherical depressions are precisely like those described by Merrill* in the serpentine of pyroxwi Montville, New Jersey, and clearly show that the serpentine in the limestone has originated from the alteration of grains and lumps of pyroxene originally present in it. The vexed question of the origin of the Laurentian serpentines is, therefore, so far as this occurrence is concerned, clearly answored. Under the microscope (Plate V., Fig. 4) the rock is seen to consist of calcite, with serpentine in rounded grains, varying in amount in the different sections, and a few scales of mica. The calcite forms a mosaic of grains of uniform size, having sharp well defined boundaries, with no intervening lines of smaller grains or other evidences of granu- lation. It presents the usual optical characters of the species, with the rhoml)ohedral cleavage and often the twinning according to — i R. The grains possess a uniform extinction. The serpentine is very v pale green, almost colourless, in the sections, and occurs in rounded forms showing aggregate polarization. It contains, however, no cores of pyroxene, the alteration being complete in the case of these small grains. The serpentine is sharply bounded against the calcite, but the serpentine grains do not possess crystalline outlines, their borders being always curved and their oiitline sometimes nearly circular. A serpen Micro8coi)ic tine grain is often completely inclosed in a single calcite individual, character. In No. 632, the serpentine grains are for the most part small and are arranged in the form of little. rings embedded in the calcite and filled with grains of the same mineral. These evidently result from the alteration of groups of pyroxene grains similar to those described below in the limestone from the River L'Assomption. The mica, which does not appear in all the sections and is never abundant, occurs in rather large leives, which are almost colourless, the light passing 1 ■ tl 'Proeredings of the Unit<'d StatfN National Mtiseuin, 1888, p. 105. 5 r *r,i 66 J QUKHEC, '••Jt through piuallfl to the cleavage having a faint brown tint It is uniaxial and negative and polarizes in brilliant colours, resembling closely the bleached biotites often seen in altered rocks. The extinc- tion is occasionally slightly uneven. One striking fact in connection with the sections is that some of the calcite grains are clear and (juite transparent while others are somewhat turV)id owing to the presence of very minute dust-like inclusions. The same calcite individual is oven in some cases clear in some parts and more or less turbid in others. This turbidity, when studied in connection with that exhibited by the calcite of comparatively unaltered limestones, such as certain beds of the Trenton, in which it is clearly seen to be derived from fragments of crinoids and other fossils about which clear calcite has been deposited in optical continuity, the outlines of the fossil fragments being frequently by no means sharp, is very suggestive of the derivation of this limestone from fossil fragments also. Against tlii-! supposition is the fact that the clearness or turbidity is usually confined to the special grain which exhibits it, instead of the grain possessing a turbid core with a clear margin, but it is nevertheless a phenomenon wiiich merits a much more extended study than it has been possible to give it at this time. CrystalHw Limestone, Riv.r fj'Assniiiptiim, ahniU 4 tnilen from Luke. L'Assomption. (^Section Oo.'t.) jjjygj. This occurrence which is expose;! by the side of the River L'Assomp- L'Assoiniition ti„n near the northern limit of the map hus already been referred to on page 24 .i. Under the microscope it closely resembles the limestone just described and consists of calcite in large grains showing no evidence of breaking, twisting or granulation, with a little ])yroxene, serpentinf and mica. While in pi ices somewhat turbid, the calcite shows but little of that suggestive arrangement of the turl)idity referred to in the case of the Rawdon rock. The pyroxene, which is colourless in the thin sections and pale green in the specimens, is arranged in little irre;^'ular groups or strings of small grains, much smaller than the calcite grain, ind which occasionally show crvstalline outlines but are usually rounded in form. These groups are often completely inclosed in a single calcite individual. The pyroxene is biaxial, and shows the usual cleavages, and inclined extinction and is frequently partially altered to seipentine. PKTnOORAPHV OF THE LAURENTIAN. 67 ,1 nt It is •esembling 'he pxtinc- jonnection and <{uite iresence of uivl is oven I in others, ited by the in i)od.s of fragments n depos'ted ents being privation of pposition is Sned to the ing a turbid enon wliich )le to give it from Luke r L'Assomp- i referred to le limestone showing no le ])yroxene, the caleite le turl)idity ne, which is peeimons, is grains, much w crystalline ps are often pyroxene is iction and is Claaa III. — Gneiaiies, .t miniature augen-gneiss, and has evi- miKeiigmiBH. jjg^tly resulted from movements in a rock having the mineralogical composition of a granite or arkose. Garnetiferous QnartzOrt/ioc/nm-Biotl/e-Gneian — Towmhip of Brandon, Range X, Lot .',. (Section HOJ. J Brandon. MicroHCopical cliaracter. The rock is rather finegrained and gray in colour, containing num- erous rounded pink garnets up to a pea in size, pretty uniformly scattered through it. Under the microscope, it is seen to be composed essentially of quartz, orthoclase, biotite and garnet, the biotite being subordinate in amount, with plagioclase, sphene, iron ore and pyrite as accessary constituents. The foliation is due to the parallel arrange- ment of the little biotite leaves and to the exi.stence of little strings of quartz running through the rock in a direction ))arallel to these. The quartz has the form of irregular-shaped individuals, often in leaves, more or less curved and running with the foliation. These leaves sometimes consist of a single individual, sometimes of several individuals, but never of granulated material. Some small grains of quartz are also seen embedded in the felspar. The orthoclase, which is abundant, never exhibits more pronounced evidence of pressure than a slightly uneven extinction, even this is often absent, and the extinc- tion is quite uniform. No evidence of granulation is seen, the several individuals coming together as in a mosaic, suggestive of re-orystalliza- tion. The biotite is in little leaves or rather large bunches. It does not sweep around the garnets, as is so often the case in similar rocks, but is often inclosed in grains of this mineral, which U evidently younger. It is deep brown in colour and pretty uniforndy distributed throughout the rock. The garnet, which is rather abundant, occurs in grains which are usually rounded, but sometimes sub-angular, and is quite isotropic. ] PBTHOURAPIIY OF TIIR LAl'RBNTIAN. G9 .1 It holds inclusions not only of the hiotite, but also of ortluxilase, (|uart/, sphene and other constituents, and presents the appearance of having grown around and inclosed them. The plagioclase is pr(>sent in small amount, the twin lines not being bent or twisted. The rock shows no cataclastic structure or other marked evidence of pressure, cither in the hand specimen or in the section, with the exception of a small eye of felspar associated with some apparently granulated material, indistinctly seen in the hand specimen, and which seems to bo connected with a little pegmatite vein running parallel to the foliation. Associated with this gneiss in the same series of exposures, which AHsociatecl occur along the road between ranges IX. and X., are a variety of other gneisses and allied rocks, interbanded with one another and lying nearly Hat. Some of these gneisses are highly quartzose, others are more basic, having the composition of a garnetiferous hornblende- gneiss. Some are the typical garnetiferous sillimanite-gneisses (Section C80) describedon page JjI j. Others again resemble amphibolites, while a few thin bands of a calcareous* gneiss or very impure limestone, as well as a few of qu irtzite, are alsci present. These rocks, like that of section 662, while free from cataclastic structure and presenting an appearance suggestive of a highly altered sedimentary .series, have nevertheless been submitted to great pressure, and have been rolled out like a plastic mass, for associated and intercalated with them are many small bands of augen-gneiss, and leat- gnciss occasionally holding little augen, which belong to the tirst class of gneisses already described and which are undoubtedly squeezed and crushed, possibly intrusive, granites. Garneti/erous Hornblende Giii'iKx — Toirnahip of Raicdon, lianye VI., Lot 2 J,. {Section 439.) This gneiss, which is dark in colour and contains an abundance of Garnetiffrons rounded pink garnets scattered through it, occurs in large exposures •'f'"'""*' interst rati tied or interbanded with a series of pyritit'erous gneisses rich in garnet and often holding graphite, which, having lieen supposed to contain gold, are referred to in the section treating of Economic Oeology, on page 148,i. Under the microscoi)e, the rock is seen to consist essentially of Hawdon. hornblende, garnet, orthoclase and plagioclase, with accessary pyroxene, biotite, pyrite, iron ore and apatite. 1 J * • ■ ' ; Oranite. Brandon. 70 ,1 QUEUEC. The hornblende, which with the garu'^t makes up most of the rock, is brown in colour and pleochroic in brown and yellow tints. The garnet is quite isotropic and holds inclusions of the hornblende, plagio- clase, pyroxene, pyrite, iron ore and apatite. The orthoclase and plagioclaso are present in aljout equal amount, and takeix together are present in about the same proportion as the hornblende. The pale- green pyroxene occurs in small quantities associated with the horn- blende, and is in part monoclinic and apparently in part rhombic. The rhombic pyroxene is partially altered to serpentine. The felspar individuals are smaller than those of most of the other constituents, and often form a mosaic showing no very pronounced pressure effects, but elsewhere occur as lines of smaller grains about and between larger ones, in a way suggestive of granulation, actual "augen," however, aie not seen. It is difficult to determine whether the hornblende and pyroxene have been produced by re-crystallization or not : they certainly have not undergone much granulation, while the garnet which makes up a large part of the rock is certainly a product of re-crystallization. The comparative absence of pressure effects, in the case of the iron magnesia constituents, as compared with the felspars, may indicate that the former in their piesent form originated during the pressure, or that during the movements induced by the pressure, the felspars: gave way more readily, allowing the movements to be cflFected chiefly through their disruption. Gneisses containing such a large proportion of hornblende are not common in the Lauren- tian of this area. Quarlz-Ort/ioclnse Gnfiss (Granulite) — Township of Bmtidon, liangi- VIII., Lot ^^. (Section o74. ) Another variety of gneiss which is very common in this region, and which is seen in many parts of the township of Brandon and else- where, resembles in many respects certain of the Saxon granulites, bein" reddish, fine-grained and nearly free from iron-magnesia constituents. It is, however, as a general rule, free from garnet, which is so char- acteristic as an accessary constituent to the Saxon granulites. The minute structure is different from, but perhaps related to, that of the gneiss of Trembling Mountain described on page 42 ,i. As a typical locality, lot 22 of range VIII, of Brandon, may be selectetl. The rock here occurs in bed-like masses interstratified with thin bands of quartzite and with some thick bands of the pvroxene- amphibolite described on page 73 j. The exposures are large and the Leds or bands lie nearly flat. The rock is fine in grain and of a pale of the rock, tints. The ende, plagio- hoclase and together are . The pale- ith the horn- art rhombic. of the other pronounced grains about lation, actual nine whether rystallizatiou ion, while the ily a product ire effects, in ed with the rni oiiginated duced by the le movements ses containing n the Lauren- liraiidon, lis region, and ndon and else- anulites, being I constituents. ;h is so char- inulites. The ,o, that of the As a typical ted. fied with thin the pyroxene- ) large and the 1 and of a pale ACMM9 ] PETROGRAPHY OF THE LAURENTIAN. 71 J reddish or pinkish colour. It has a somewhat indistinct foliation and is uniform in character over large exposures. Under the microscope it is found to consist, for the most part, of microperthite, the individuals of which are sometimes seen to he twisted, but not in a very marl ul manner. Quai tz, sometimes in leaf -like forms, is present in smaller amount and shows similar though less marked evidences of pressure. A few grains of black iron ore, probably magnetite, a small amount of a chloritic decomposition-product derived from some bisilicate which has entirely disappeared, with a few little colourless rounded grains of zircon or possibly monazite, are the only other constituents of the rock. The minute structure differs from that of the Trembling Mountain rock in being fine in grain throughout, the larger individuals described in that rock being absent. It Probably a crushed resembles, in fact, the fine groundmass of the Tremblip Mountain granite. rock, consisting of minute angular and more or less rounded fragments indiscriminately mixed together. From a study of the sections, no decided proof can be obtained that this is cataclastic structure, but it is just the structure which would be produced if the process of granulation, described in the case of the Trembling Mountain gneiss as in progress, were completed, the original structure 1 eing entirely destroyed. If the banded character of the rocks of the district has been produced by a process of stretcliing or rolling out, the movements and concomitant granulation must have been very much more intense than was necessary to produce merely an indistinct foliation as in the Trembling Mountain rock ; or tlie original rock may have been finer in grain. The evidence of pressure in the case of tlie orthoclase would, as lias been shown in the case of the Trembling Mountain rock, be less marked in the finely granulated material than in the larger remnants, if any remained. Therefore, although the rock may have been produced in some other manner, iLs minute structure is just such as would be caused by the intense crushing of a granite rock, and Professor Kosenbusch believes it to he merely a crushed granite. Another class of rocks found sissociated with the orthoclase-gneisses Pyroxene-' in all parts of the area, but very aliundantly in the t<^wusliip of pyroxene- Brandon and the adjacent parts of the eastern portion of the area, K>'n"iilites. are pyroxene-gneisses and pyroxene-gran ulites. These rocks differ from the orthoclase-gneiss in colour, being usually yellowish, brownish or black on the fresh fractuie. Although usually indistinctly foliated, they are frecjuently nearly massive and uniform li Il-J 72 J QUEBEC. Rhombic and monocliiiic pyroxenes. Character of the rocks. Quite distinct from normal granulites. in character over large exposures, in this way differing from the usual run of the associated acid gneisses. Their constituent minerals cannot as a general rule be determined from the study of a hand specimen, but under the microscope the rocks are found' to have a composition which varies but little. Pyroxene is always present as an essential constituent, both rhombic and monoclinic varieties usually occurring together. Hornblende, usually green but sometiuies brown in colour, is sometimes but by no means always present. Biotite when present at all is very subordinate in amount. Plagiocluse is usually the predominating felspar, but orthoclase is very often present as well, and is sometimes as abundant as the plagioclase. Magnetite, apatite and a few other accessary con- stituents (jccur in small amount. These rocks are very seldom coarse in grain, being generally rather fine-grained to nearly compact. They may be separated into two classes which, however, have no sharp dividing line and pass into one another by imperceptible gradations. One class would embrace the coarser grained varieties, which are usually somewhat poorer in the iron magnesia constituents and occur in large bodies, and which may be called pyroxene-gneisses. The other class comprises the fine-grained and nearly black varieties, which occur very frequently interhanded with granulite and other forms of orthoclase gneiss, in all parts of the area, and which from their resemblance in character and mode of occur- rence to the " trap-granulites " or " pyroxene-granulites " of the Saxon granulite gebirge may be called pyroxene-granulites. This latter name has certain disadvantages,* among others the fact that the rock bears no resemblance to true granulite, but as the name already has a status in petrographical nomenclature from the thorough description which has been given of the petrographical character and mode of occurrence of the rock in the tSaxon granulite gebirge, as well as owing to the circumstance that every other name already in use and which might be applied is attended with equally great objections, it will here be employed to designate the rocks in question. These pyroxene-granulites when they become rich in hornblende and poor in orthoclase might be termed pyroxene-amphibolites. As typical examples of these pyroxene granulites and pyroxene amphibolites the following rocks may be taken. ' See Zirkel, Lelirbncii dcr IVtro^raphie, vol. III., \>. 2.*)1. PETROGRAPHY OF THE LAURESTIAX. r3 J Pyrorene-Amphibolite — Range VIII., Lot 2^, Township of Brandon. (Section 571.) and pyroxene In the hand specimen, the rock is seen to be rather fine in grain, Pyroxene- nearly black in colour, and to possess an indistinct foliation, with occa- ""Br^^'^o,] sional narrow bands in which one or other constituent predominates. It occurs in thick bands interbanded or interstratified witli the granulite described on page 70 .i. Under the microscope, the rock is found to consist essentially of horn- blende, pyroxene and plagioclase felspar, with a small amount of orthoelase felspar and a little magnetite, apatite, and prol ably a few grains of quartz. The hornblende is deep bro^vn in colour and strongly plecchroic, and is present in large amount. There is no evidence that it has been derived from the pyroxene and it often occurs in compar- atitely large individuals. The pyroxene, which is also present in large amount, is in part hypersthene, showing the usual nleochroism in yellow, red and green tints and a parallel extinction. Some monoclinic pyrox- ene is also present. None of the constituents have even an approxi- mately idiomorphic development. AH are in irregular-shaped grains. The foliation, which is parallel to the banding, is indistinctly seen in Microscopical t^p thin sections, but there is a development all through the sections of granulated material in little strings or streaks running in one direc- tion. This is composed largely of plagioclase, but hornblende and pyroxene are also seen in a granulated condition, mixed with the pla- gioclase. Almost every one of the larger grains of plagioclase shows the effects of intense pressure, in well marked strain- shadows, twisting of twin lamella' and breaking into smaller grains. It is a fact of interest that, in this as in many similar cases, the hornblende and pyroxene, although in places granulated, do not when in large grains siiow uneven extinction, while what in ordinary light appear to be grains of plagioclase of similar size, invariably, when examined between crossed nicols, are seen to be crushed aggregate of small plagioclase grains. The examination of this rock under tlic microscope makes it certain that whatever the origin of the I nding maj- be, the foliated structure is not original, but has been produced by movements in the rock which were accompanied by a granulation of its constituents. The hornblende may possibly be a secondary product. IP : !| 74 J QUEBKC. Cheiiiicnl A specimen of tlie rock analysed for me by Mr. "Walter C. Adams, coiiiiKiaition. 13 .^gp^ ^ag found to have the following composition : — XI. Fyroxene-Amp]iib»Ute — Township of Brandon. Per cent. Silica 4ll'C Aliimiiia ... 17 '53 Ferric o.\iH OSJf.) Occurs interstratitied with granulite, the whole being cut transversely by pegmatite masses which have lieen crushed to an augen-gneiss, the foliation of which coincides w ith the banding of the series (see Figs. 4 and 5). The rock has an i.Hlistinct foliation when seen in large exposures, but no foliation can be noticed in hand specimens. It is dark in colour and rather fine-grained. *A11 the iron is calciilatcfl as ferric oxide. C. Adaais^ Per cent. 4!l 7« 17 53 10 (52 36 10 57 7-90 3 05 •80 ■34 100 -99 nd diabases. 3ne-granulite xene, pi agio- ore scattered yroxene. It the presence 16 rest of the i much twist- I undergone a the rock has t of pressure ; decided from f Brandon. GEOLOfilCAL SURVEV OK CANADA. Fig. 1. Vol.. Vin., Part J. Fta. 2. i'^f Fi(i. 3. Fio. 4. t transversely ;en-gneiss, the s (see Figs. 4 •ge exposures, dark in colour PLATK V. Fr(i. 1. - Pyroxenegranulite, range VI., lot 13, township of Braniion— Plagicxjlase, Pyroxene and Iron Ore. X 2!>. Fig. 2.— Pyroxenfamphibolite, TBEMnrrNo MoUN'i'y> in— Hornblende, Pyroxene, Plagioclase and Iron Ore. V 20. Fig. 3.— Pvuoxknb-gnkiss, Sr. .1 han he Matha— Pyroxene, Felspar and Iron Ore. X 30. Fig. 4.— Sehpentink-i.imestose, range X., lot 27, township of Rawoon— Calcite (in places twinned) and Serpentine. X 11. i!* M m II H^'-^bft m k: OCCl andF ■] PETROGRAPHY OF THE LAURKNTIAN. 78 J \ It is coDiposed of pyroxene, vhich is lor the most part augite, pale- green in colour and with barely pt'-^eptible pleochroism, together with plagioclase and a good deal of iron ore. There are also a very few grains of pyrite. The rock contains no h nblende, biotite or ortho- clase. The structure is allotriomorphic, ar although the felspar shows faint indications of strain the pyroxene is never granulated, and the rock looks as if it had been crystallized in situ (Plate V., Fig. 1). The granulite (Section 685), which is interstratitied wi*-h it does not form continuous bandst but thins away when foUowea .tiong the strike. It is composed of quartz and orthoclase, and has an appearance which is highly suggestive of extensive { t>,n ' tion, for although all the grains are small, there are often smaller ones which appear to have been formed by the breaking down of the i.irger, and in a few placei tiie peripheral granulation of the orthoclase could be observed. That both rocks must have undergone a decided rolling out under pressure, in the direction of the bands, is proved by the conversion of the inclosed pegmatite veins into an augengneiss with a foliation in this direction. /'yroiene-G'ranulite — Range VIIL, lot "'^ ^mvnsliip of Brandon, (Section 683), Forms a large mass which is the northerly continuation of the occurrence last described. It shows, however, distinct differences in mineralogical character, proving that the rocks of this class vary some- what in their nature from place to place, even in the same masses. The aug m-gneiss and granulite are here absent. The pyroxene is pale-green in colour as before, but most of it is rhombic in character, with strong pleochroism in reddish and greenish tints and parallel extinction. An untwinned felspar which is prob- ably orthoclase is also present, and is more abundant than the plagio- elasf. Very small amounts of hornblende, biotite, pyrite and zircon are also found, as well as a. considerable amount of apatite in rather large individuals. Iron ore occurs in rather large amount, often partly inclosing the pyioxene, as is frequent in these rocks. The appearance of the rock under the microscope, is suggestive of granulation. Vyroiiene-GraniiHte — Range VIII., Lotti !) and 10, Township of Bran- don (Sertion SoO). This rock forms large exposures about one mile to the east of the other occurrence last described. The rock is here fine grained, very uniform I'yroxiiie- , ... Kraimntes and nearly massive. It is never banded, and in places no foliation frdiiiHrj'iiihni. JH , * ' i; •I .\[ i Ml 76 .1 QUEHEC. can be detected. Between these exposures and those lost described the pyroxene granulite is associated with granulite plainly derived from a granite by crushing, as it frequently contains remnants or augen , of as yet uncrushed orthoclase. The rock is composed of rhombic pyroxene and plagioclase %* ith some orthoclase (untwinned), but also contains much hornblende and biotite. A small amount of augiteniay also be present. Iron ore, pyrite and apatite are accessary consti- tuents. The hornblende, which is green in colour, is about equal to the pyroxene in amount, and the biotite to about one-half the amount of either. All three minerals are intimately associated. There is no evidence that the hornblende or mica are secondary, although the mode of occurrence of the latter suggests that seen in certain contact rocks such as hornstones. The plagioclase is broken and twisted in placefs and the rock looks like a granulated one, but if so there are no large remnants left. Pyroxene-Grannlite — Range IX, Lot 16, Toirnahip of Bramhn, (Sectiou OSJ). Otlitr This rock, which in the field closely resembles the last two, occurs emiiiHtes rather over a mile to the west of No. 683, which it closely resembles fioiriBrantloii. also in composition and microscopical character, and from which it is separated by bands of granulite and other varieties of gneiss. It contains large intercalated masses of nugen gneiss, whose foliation coincides in direction with the banding of the whole series. The pyroxene is chietly rhombic, but monoclinic pyroxene is also pre- sent. Both minerals are pale-green in colour, and can be distinguished only by their optical properties. The rhombic pyroxene (probal)ly hypersthene) shows the regular pyroxene cleavages with parallel extrac- tion in sections parallel to the vertical axis. Prismatic sections ex- hibiting the cleavage parallel to ooP^, when examined in convergent light show this to be the plane of the. optic axes. The mineral is dis- tinctly trichroic. a = red, ft =r yellow, r =^ green. The monoclinic pyroxene ii not pleochroic, has a hif^her double refraction and shows an inclined extinction. The plagioclase and an untwinned felspar, probably orthoclase, are piesent in about equal amount. Biotite and green hornblende occur in very small quantity, as.sociated with the pyroxenes. A few grains of pyrite and apatite are present in each section, as well as some iron ore, which usually incloses grains of pyroxene — a peculiar mode of occurrence often found, however, in these rocks. (See page 79 .J.) iv.h ] PETKOORAPHV OP THE LAURENTIAN. n J B last described plainly derived mnants or augen jsed of rhombic irinned), but also nt of augite may iccessary consti- s about equal to l)alf the amount d. There is no ry, although the 11 certain contact 1 and twisted in f so there are no I) of Branifoii, i last two, occurs closely resembles id from which it ies of gneiss. It whose foliation series. 'oxene is also pre- i be distinguished •oxene (probal)ly ,h parallel extrac- natic sections ex- ed in convergent le mineral is dis- The monoclinio action and shows ily orthoclase, are hornblende occur A few grains ^ell as some iron peculiar mode of le page 79 .i.) None of the constituents have good crystalline form. The foliation OriKin of is produced by the arrangement of the pyroxene grains with their " longer .ixes in one direction. Almost every grain of felspar shows strain-shadows or fractures. It is difficult to say wliether the peculiar granular character of the rock has been produced by movements or not. Tlie pyroxene does not show ^tty evidence of granulation although it occasiimally shows strain shadows. Under a low power, however, the sections exhibit an appearance of extensive granulation and suggestive of the possibility of the rock having been deformed by the granulation of the felspar with a certain movement of the pyroxene individuals through the granulated mass. Separated from the pyroxenegranulite on the east by a mass of very rusty-weathering gneiss, and associated with granulite proper, is an- other rock resembling the one here described in appearance, but which is, in places, rich in garnet. A section (No. 686) of the garnetiferous variety, however, showed the rock to be composed essentially of red garnet and dark green hornblende with some pyroxene. The garnet is • (juite isotropic and felspar is absent. Pyroxene- Amphibol lie — Trembfhig Mountain. (Sertion n3G,) In describing the geology of Trembling Mountain (see page 42 j) it pyvoxene- was mentioned that the existence of thin bands or stratiform masses of n;"'pl>;''9lit«- Iri'iiibling a black pyroxene-amphibolite at long intervals interrupted the uni- Mountain. formity of this great mountain-mass of granulated gneiss. This pyroxene-amphibolite is idetitical in character with some of the pyroxene granulites just described. It consists essentially of hornblende, pyroxene and plagioclase, with very small amounts of iron ore, apatite and biotite as accessary constituents. The horn- blende is green or sometimes brownish-green in colour antl strongly pleochroic, as in the as.sociated gneiss. The pyroxene, which is chiefly rhombic in crystallization, is not quite so abundant as the hornblende. The plagioclase is present in large amount and in well twinned grains. There is no evidence that the hornblende has been derived from the pyroxene. Although in the hand specimens the rock looks more massive than Mieroscopicdl the associated gneiss, when examined in thin sections under the micro- ^liivracter. scope it is seen to possess a distinctly foliated structure (Plate V., Fig. 2). None of the constituents have any approximation to an idio- niorphic form, the rocks consisting of a mosaic of irregular- shaped grains. The felspar grain-, while irregular in shape are about equal i >' 1 i ';i':ly| 78 J QUEHEC. in all dimensions, and form a sort of groundmass, in which the horn- blende and pyroxene, which have a tendency to assume elongated forms, are distributed as irregular, discontinuous, anastomosing strings. This rock, although, from its existence in the foliated gneiss shown to have been submitted to enormous pressure and probably sciueezod out by this into its present band-like form, attbrds no absolute proof of the granulation so well seen 'in the gneiss which incloses it. The felspar grains, nevertheless, may have lieen produced by granulation. The bisilicates often occur in little granules like those seen in the granulated anorthosites, although they usually a.ssume thn ratlier elongated forms, above referred to. It is in fact in all probability a granulated rock, although the absence of large remnants makes proof of this impossible. It is probable that these occasional interrupted bands or elongated masses of pyroxene-amphibolite in the crushed granite represent basic secretions in the original rock, such as are found in granites in all parts of the world. Pyroxene-Gneiss — St. Jean de Hatha, near the church. {Section 35S.) S ■! Pyroxcim- giieiss. — St. Jciiti de Matlui. Two fel»i)ai'.s. The rock is dark-gray in colour and while distinctly foliated has a pretty uniform character over large exposures. In the thin sections it is seen to consist essentially of pyi-oxene, felspar and ir^^n ore. Biotite and hornblende are present, but in very subordinate amount, together with a few grains of p3'rite and apatite. The pyroxene is in part hypersthene and in part augite, the relative proportion of the two varying in different sections, but the hypersthene on the whole preponderating. The hypersthene shows the usual tri- chroism in reddish, greenish and yellowish tints and is free from all schillerization inclusions. The augite closely resembles the hypersthene in appearance, but has an inclined extinction and is not pleochroic. The two pyroxenes are intimately a.ssociated. Two" felspars are present in about equal amount. One is a well twinned plagioclase, presenting the usual characters ; the other is an untwinned felspar, which is frequently obsei-ved in these rocks and which is in all probability orthoclase, its most noticeable cliaracteristic being the appearance of pale bluish and brownish tints respectively, when between crossed nicols the section is turned slightly on either side from the direction of maximum extinction. The phenomenon appeal's to result from a slight dispersion of the bisectrices. ivhich the horn- )longated forms, ig strings. k1 gneiss stiowu obably sfjueezed ibsolute proof of ncloaes it. The by granuhitioii, )8e seen in tlic ume thn rather ill probability a ,nta makes proof (Is or elongated represent basic inites in all parts /,. {Section 35S.) ly foliated has a he thin sections ,r and ir'^n ore. rdinate amount, gite, the relative the hypersthene i?s the usual tri- is free from all the hyperstheiip not pleochroic. One is a well ; the other is an these rocks and l)le characteristic nts respectively, ilightly on either ■'he phenomenon irices. PKTUOOHAPIIY OK THE LAIRKXTIAN. '9 .r The iron ore, which is, after the pyroxenes and felspars, the most interpn.wth abundant constituent, is black and opaque, and when examined by "' "'"" '"'''*■ reriocted light often presents certain bands and spots differing slightly in lustre from the rest of the grain, which indicates the intergrowth of two sorts of iron ore probably diU'ering in content of titanium, as described in the case of the Morin anorthosite. Its mode of occur- rence, however, is very peculiar, being found in between the bisilicates generally in long, narrow grains, and often nearly or completely sur- rounding the latter (see Plate V., Fig. 'A). It was in one ease observed to have the form of a narrow band cutting across a pyroxene grain and continuous with a mass of iron ore on either side. It was evidently formed after the bisilicates had crystallized. Tiie same phenomenon was observed in the case of certain anorthosites very rich in iron ore (see page 100 .1). Distinct evidence of crushing, in the existence of ^''"" ",''■ , augen or marked twisting of constituents, is absent, but the rock latti ilmn nevertheless looks as if it might have undergone a thorough granula- """ "■""'■'*• tion. Traces of this are, as usual, much more marked in the felspars than in the pyroxeaea. A pyroxene-gneiss (Section 305), almost identical ivith that just described, forms large exposures in lot 10 of ranije XI. of the town- ship of IJrandon, between the Lac Corbeau and the second anorthosite band. /'i/ro.vfinn-Gni'Iss — Sei'/niory of D'A'tlhliont, ahout one mile X.E. o Range III. 0/ (Jn- ToiniKhip of Cat /i car f. (Section ,299.) This rock was chosen as a typical representative, not only of large Pyroxeiip- exposures in the innnediate district, but of the basic gneiss, intimately '|'"'^'^n .| , » associated and interbandel with the red ijuartzose orthoclase gneiss, in very many widely separated parts of the area covered bj' this report. The rock is bluish on the fresh fraetun", ijut weathers gray, and has an indistinct foliation coinciding with that of the associated quartz- ose orthoclase-gneiss. Under the microscope it is found to consist essentially of pyroxene and plagioclase. A considerable amount of untwinned felspar, some of it prol)ably oithoclase, is also present, as well as a little hornblende, biolite, iron ore, pyrite, apatite and oalcite. The pyroxene is for the most part hypersthene, identical with that in the rock last described. The hornblende, which is green in colour, is apparently derived, in part at least, from the alteration of this pyroxene. The iron ore, as before, is often found partially inclosing the pyroxene. The occa- sional presence of leucoxene as an alteration jlroduct indicates that it I !:■*': ii' t ■ A-- -'m IMAGE EVALUATION TEST TARGET (MT-3) . I 1.0 ^^ Ui ■tt Itt ■2.2 I4& 110 I.I W Mt 1.4 1.6 6" ^ J^ // r '^ Hiotographic ScMioes CcrpoiHticHi <^ n WKT MAM STRHT WnSTII,N.Y. 14SI0 (71«)S72<4S03 4^ \ Evidence of granulation. Pyroxene- gneiiiB in in Sagiienay region. Common in Lower Archaean. Origin of pyroxene. 80 J QUEBEC. is a titaniferous variety. The calcite is secondary. In addition to the plagioclase, presenting the ordinary characters as seen in those gneisses, there are a number of individuals which are very clear and " polarize brightly, resembling the secondary plagioclase often devel- oped in crushed rocks. As in the case of the pyroxene-gneiss just described from St. Jean de Matha, although there is no absolute proof of granulation, it is almost certain that the rock has been subjected to this process; strings of fine grains are everywhere seen in and about the larger grains, and the appearance is that of a granulated rock. Here again the evidence is principally seen in the felspars. Pyroxene-gneisses identical in character with those just described, as has been mentioned, are very abundant in the area embraced by the accompanying map, but especially in that part of it lying to the east of the Morin anorthosite. They are also found widely distributed in the Laurentian elsewhere, as, for instance, in the Saguenay district. They differ from the associated acid gneisses not only in composition but in having a darker colour (never red like the orthoclase gneisses), a more uniform character, and more massive appearance. They never contain quartz. These pyroxene-gneisses and pyroxene-granulites, formerly thought to be very uncommon rocks, have in recent years been described from a great number of localities in all parts of the world, and will probably be found to be one of the constant elements of the lower Archn^an wherever that is extensively developed. A brief review of these various occurrences, with full references to their literature, is given in a recent paper by Professor Judd.* The origin of these rocks is a question concerning which, even in the localities where they have been most thoroughly investigated, there have been great diversities of opinion. In the district in which pyroxene granulites were originally described, for instance, the granu- lite region of Saxony, Nauiiinn believed them to be eruptive, Stelzner and others consider them to be metamorphic products, while Lehmann, who has made a more recent and very thorough study of them, con- siders the question of their origin as still an open one. The mode of occurrence of the pyroxene-granulite in Saxony and the intimate rela- •The Rubies of Burma and AsKociated Minerals, their mode of occurrence, origin' and metamorplioses. Phil. Tra' «., 189C, \t. 192. Also A. Lacroix— Contributions h letude des Oneiss k Pyroxene — Bull. Soc. AJin.,. France, April, 188!). ] PETROriRAPIIY OF THE LAURENTIAN, 81 J iddition to n in those J clear and ften devel- m St. Jean ation, it is ess; strings grains, and le evidence escribed, as ced by the to the east tributed in ay district, composition le gneisses), They never rly thought cribed from ill probably jr Archjvan !W of these ire, is given which, even nvestigated, ict in which , the granu- ve, Stelzner e Lehmann, them, con- riie mode of ttimate rela- urreiice, origin' nil. Soc. >liii., tion which it bears to the normal gra/iulite, the two rocks being con- ( inelHses and nected by a complete series of intermediate varieties, points very '^'"*"" "*"• strongly, in the case of the Saxon occurrences, to the origination of both rocks in thedifferentiation of an original igneous magma. The chief difficulty in considering the pyroxene-granulites of Saxony as dif- ferentiation products from the same magma that gave rise to the normal granulite, is the fact that they are practically massive and have been considered to show no evidence of crushing, while the accompanying granulite is seen to have been crushed and granulated in a very miirked manner. The pyroxene-granulites of the district embraced in the present Saxon Report, differ from those of Saxony chiefly in being a little coarser in grain and in possessing, as a general rule, a more or less indistinct schistose structure. Garnet also is a less frequent constituent. That these Canadian rocks, whatever be their origin, have been Cni-died |)eg- greatly compressed and rolled out like plastic masses (although ""''*'**^ '"*^'"'''" no conclusive evidence of the fact can be seen in the minuie struc- ture of the rock) is placed beyond a doubt by the presence in them of sharply folded, crushed and foliated masses of pegmatite converted into augen-gneiss and leaf-gneiss by the pressure, the foliation running in one plane through the whole body of the rock and being quite independent of the position of the pegmatite masses. That the present attitude of the rocks was not their original one, is also plainly shown in Figure 8, where a dark-coloured pyroxene-gneiss, containing a good deal of quartz, is seen to lie as a series of sharp folds in a mass of leaf-gneiss. The axis of these folds is now the strike of the rock, but it is evident that the pyroxene-gneiss originally formed a band, dyke or arm in the lighter coloured quartzose orthoolase rock, running Figftiro 8.— Dark Pyrox«Mie-Gnei88 folded in a mass of Li^af-Uneiss, Range VIII., Lot 18, Township ot Brandon. Scale 8 feet to 1 inch. in u direction highly inclined or possibly at right angles to the pre- sent strike. This is by no means an isolated case or confined to this locality ; the same phenomenon can be observed in very many places in this as well as in other Laurentian areas in various parts of the Dominion, and when the folds are longer and more compressed their 6 ■:<'. i I;. 'I villi F' 1 m 82 J QUEBEC. Microgcopical character unlike that of gabbro. IMI fl Sca^)blite- gneiiis. Kttwdon. resemblance to interetratified bands, especially in small exposures, is much more marked. The microscopic structure of the pyroxene-granulites, as a class, is quite distinct from that of the undoubted igneous rocks having the same mineralogical composition (the gabbros), but after the study of a large number of sections of these rocks from various parts of Canada, as well as from the Saxon granulite region, I am unable to see that their structure precludes them from being considered as granulated rocks, although no direct evidence of crushing may be afforded by them. The indications of granulation in the case of the Canadian rocks have already been referred to in the description of the sections. Much light might be thrown on the origin of these peculiar rocks by a thorough study of their chemical composition, with a view to ascertaining whether they all, like the pyroxene-amphibolite from Brandon (No. 571), have the composition of gabbros and diabases, or whether some of them have a composition different from that of Igneous rocks. At present the origin of these Canadian occurrences must remain a matter of doubt, although the argument in favour of a nietamorphic origin in the case of the Saxon rocks, from alleged absence of granu- lation and other pressure phenomena, does not, as has been shown, apply with equal force to the pyroxene-granulites of Canada. Orthoclase-Scapolite-Pyroxene-Gneiss — Township of Rawdon, Range VII., Lot 20. (Sections 597, 630.) This gneiss, which weathers to an exceedingly rusty colour, occurs in bands interstratified with a grayish-weathering, garnetiferous gneiss, traversed by many little veins of quartz. Across the road on the same lot is the band of garnet rock described on page 84 .i. It is fine- grained, greenish-white in colour, and on a fresh fracture presents a finely-speckled appearance. As has been mentioned, it weathers very rusty and disintegrates so readily that it is difficult to obtain speci- mens which are really fresh. It has a very indistinct foliation. Under the microscope, it is seen to be composed essentially of ortho- clase, pyroxene and scapolite, with accessary pyrite, pyrrhotite, graph- ite and sphene. The pyroxene, which is very pale green in colour, has the characters of malacolite. The scapolite is colourless, uniaxial and negative, with cleavages crossing at right angles on basal section, and parallel extinction in sections in the plane of the vertical axis. The sulphur, if calculated as pyrite, would show the presence of nearly Ktsures, IS a class, is laving the itudy of a f Canada, ,o see that ;ranulated 1 by them, "ocks have iliar rocks a view to olite from iabases, or n that of t remain a jtamorphic of granu- len shown, on. Range our, occurs rous gneiss, oad on the . It is fine- presents a athers very btain speci- tion. lly of ortho- itite, graph- i in colour, )ss, uniaxial »sal section, jrtical axis, ce of nearly ] PETROGRAPHY OF THE LAUREMTIAN. 83 J four and a half per cent of that mineral, but, although much pyrite is present, there is a good deal of pyrrhotite present as well, the two minerals being intimately associated. These two minerals almost certainly represent a later impregnation, occurring, as they do, in little irregular-shaped masses, with minutely banded structure parallel to their sides, as if filling cavities. They are sometimes decomposed to haematite, the pseudomorphs being often remarkable in that they consist of a single individual. The ferric hydrate which stains the weathered surface of the rock is also derived from their decomposition. The graphite occurs as little flakes, and is often intimately asso- MicroHcupical ciated with the pyrite, suggesting some genetic connection in the case ''"*''"""^*''"- of the two minerals ; as, for instance, the formation of the sulphides from the reduction of iron-bearing solutions through the agency of organic matter, a portion of which still remains as graphite. The sphene, which is seen in every slide, is pale brownish in colour, and occurs in more or less elongated grains lying in the direction of the foliation. It has the usual high index of refraction and high double refraction, with an extinction generally inclined at a small angle to the longer axis of the grain, and is often twinned. The rock pre- sents the appearance of having been produced by a complete crystalli- zation or re-crystallization of the various constituents in silu, the grains of felspar having sharp polygonal outlines, and the individuals of the several minerals fitting together like the pieces of a mosaic, no fiigns of granulation being visible. A specimen of this gneiss was analysed by Mr. Walter C. Adams, Cliemical B.A.Sc, and was found to have the following composition :— ci.ini«8itioii. XII.—Orthoclase-Scapolite-Pyroxene-Gneiss — Townnhip Range VII., Lot 20. of Rawdon, Per cent. Silica.. 54 Titanic oxide 1 Alumina 13 Ferric oxide 1 Ferric Hulphide 4 ManganouM oxide Lime 5 Magnema 4 Soda 1 PotPHsa 8 Water and graphite (by difference) 2 Total alkalies. 100 00 . 10 2!t 80 (Hi 67 35 43 02 G3 70 95 34 70 ^ T^,'i I 84 J QUEBEC. (Jftmet n»ck This gneiss, as will be seen, differs entirely in composition from any of those Qf which the analyses have already been given. The low content of alumina, combined with low silica, the high alkalies and the preponderance of lime over magnesia, mark it off as quite distinct from the slates and sedimentary gneisses before considered. If it be an altered sediment, it is one which has suffered very little leaching during deposition, and must have been of the nature of a tuffaceous deposit, or one formed from the rapid disintegration of an igneous rock having the composition of a basic trachyte or syenite. It is, therefore, a rock which, so far as its composition is concerned, might be either an altered sediment or an altered igneous rock ; and it is impossible, consequently, to draw from its chemical composition any definite conclusions as to its origin. The graphite, however, points to a sedimentary origin. Specimens of another band of gneiss (Section 385) similar in general appearance to that just described, and occurring near it, were found upon microscopic examination to differ from it in holding a consider- able amount of garnet and plagioclase, as well as some quartz, but no scapolite. The pyroxene is very pale brown in colour, and the garnet, which as usual in the Laurentian gneisses is quite isotropic, holds as inclusions grains of the various other constituents of the rock. Intimately associated with the garnetiferous gneisses, and probably representing an extremely garnetiferous variety of them, are the bands of garnet rock described from two localities under the heading of Economic Geology (p. 150 J.) At the first of these localities — the rear of lot 20 of Range VII. of the township of Rawdon — several bands of the garnet rock are found, the widest being about two feet thick. They occur interstratified with fine-grained garnetiferous gneiss and white quartzite. In some parts of the bed the garnet rock is almost pure, while in others it is seen to contain a little quartz, b'otite or felspar. The purer portions (Sections 440, 654) when exa'uined under the microscope aia seen tu consist almost exclusively ol pink garnet. Some iron ore, with a little biotite, and in one section a grain of green spinel, are the only other constituents. The garnet occurs in very large individuals, which are isotropic and almost free from inclusions, with the exception of a few grains of biotite. The iron ore is black and opaque and occurs chiefly in the form of large angular grains. The surfaces of the garnet grains are often stained with a little ferric hydrate. The biotite and iron ore are inclosed in the garnet and have the appearance of having origin- ated contemporaneously with it. In some sections (No. 654) a little plagioclase is present. ] THE MORIN ANORTH08ITE. 85 On lot 22, of range IX., of the townslyp of Rawdon, a heavy band Pyroxene of granular brown pyroxene rock occurs, associated with garnetiferous ^'^ graphitic gnei) the Ottawa Lake in the itagne Noire thosite area ding gneiss. y consulting te has been bhosite mass, urves of the a portion of , in part at least, a secondary structure, induced subsequent to the intrusion of the anorthosite by great pressure, which pressure has affected the anorthosite as well — for the anorthosite, especially near the contact on the eastern side, possesses a distinct foliation coinciding in direction with that of the gneiss. The arm-like extension of .the anorthosite through the gneiss to the south-east becomes somewhat wider as the plains underlain by the Palteozoic are approached, being divided longi- tudinally by a wedge of gneiss which runs into it from the south, and which with the anorthosite becomes covered up by the overlying Palteozoic rocks. The anorthosite of this arm, like the gneiss itself, dips to the west, being therefore on the western side overlain by gneiss. The angle of dip, however, varies much in different places. Although in many parts of the circumference of the area, the Contact anorthosite comes against the gneiss without producing any perceptible '' "*"'■ alteration, yet in some places, and especially between Hhawbridge and Chertsey, a dark heavy rather massive rock, rich in bisilicates and often holding a little quartz and some untwinned felspar, borders the area and may possibly be a contact product of some kind. The boundary of the typical anorthosite against this intervening rock is usually pretty sharp, while the latter passes over gradually into the gneiss of the district. It is, however, difficult to decide whether this rock is to be considered as a peculiar and abnormal (possibly altered) variety of gneiss, or as a contact phase of the anorthosite. What is apparently the same rock, or a very similar one, occurs largely developed at the north-west corner of the area, between the typical anorthosite and the gneiss. Stratigraphical as well as microscopical evidence indicates that here it is a peculiar variety of gabbro, nearly or quite massive, but sometimes showing a scMieren structure. This breaks through the gneiss, but is apparently continuous with the rest of the anor- thosite mass. Continuous exposures from one rock into the other, enabling the relations to be determined, have, however, nowhere been found, but the evidence goes to show that this gabbro forms part of the anorthosite area and is not a separate intrusion, although the transition is rather abrupt. At a number of places near the limits of the area, especially about Gneisn the dividing line between the rear ranges of Wexford and Chertsey, '"•'"'*"'"8' near the road to St. Donat, very large masses of orthoclase gneiss occur inclosed in the anorthosite, and afford additional proof, if any be required, of the intrusive character of the latter. Thoi^e occurring about the line between Wexford and Chertsey, lie approximately in the direction of the prolongation of the strike of the great tongue of gneiss which runs 88 .1 gUEBKC. Pegmatite veiiiti. Sir William Logan's views. up between the main mass of the anorthosite and the arm-like pro- trusion from it, and probably represent a former extension of the gneiss in this direction, shattered and invaded by the anorthosite. Similar inclusions of gneiss are also seen near the margin of the Morin area in the rear of the township of Doncaster, being exposed on the road running south from Lake Archambault to Ste. Lucie, and along the River Ouareau where it crosses range VIII. of Chilton, A very large mass of gneiss, some five miles long and two miles wide, is also inclosed by the anorthosite near the east side-line of the township of Chertsey. The anorthosite is in many places penetrated by coarse pegmatite veins. These are especially abundant near the edge of the area, cut- ting botli gneiss and anorthosite, so much so, that an approach to the boundary may often be surmised from their appearance in large numbers. These pegmatite veins, however, are by no means restricted to the margins of the area but are abundant in places near its centre. They are composed of quartz and orthoclase, often with a little iron ore, and are thus quite diderent from and apparently uninfluenced by, the composition of the anorthosite through which they cut. A nuuil)er of other occurrences in the township of Wexfoi-d, which are probably of the same nature, were found to hold the same bisilicates as the anorthosite. None of the rarer minerals frequently found in such veins were observed, except one which occurs in the thin sections of a single specimen, and which resembles allanite In the township of Wexford, along the road which runs south-west from Lac des lies between ranges YIII. and IX., there is a great VxKly of highly quartzose rock, much of it an almost pure <|uartzite, inclosed in the anorthosite. It extends along the road for about two miles, varying considerably in width, but near the lake being over a quarter of a mile wide. This mass may be an inclusion of gneiss, such aa those referred to above, but much of the quartzite has an appearance suggestive rather of vein origin (Section 437). Both the anorthosite and the gneiss are cut by numerous dykes of diabase and augite porphyrite. In order to understand why Logan, and other good observers follow- ing him, regarded these anorthosites as constituting a distinct overlying series, a brief review of the grounds on which he based this view may here be presented. On working out the geological structure of the Grenville district, which district lies immediately to the west of that embraced in the pre- ] THE MORIN AN0HTII08ITE. 89 J n-Hke pro- the gneiss ■gin of the BxpoNed on Lucie, and hilton. two miles ine of the pegmatite s area, cut- pproach to ice in large s restricted • its centre. little iron nintluenced ey cut. A , which are ) bisilicates ly found in lin sections south-west great Vxxly te, inclosed two miles, »r a (|uarter iss, such aa appearance IU8 dykes of ■versfollow- ct overlying is view may He district, 1 in the pre- sent report, the two overlapping Homewhat, Ix)gan recognized three principal bands of crystalline limestone which he called the Trembling l^ke hand, the Green Lake band, and the Orenville band respectively- The limestone above mentioned as abutting against the anorthosite at >St. tSauveur, was believed to be a portion of the Green Lake bund. Sir William referring to the band as having been " interrupted " by the Morin anorthosite. Further to the north, in the township of DeSala- berry, he found that two of the limestone bands again came in con- tact with this anorthosite mass, one of them being this same Green Lake band and the other the Trembling Lake band. Sir William refers to this occurrence as follows (Geology of Canada, 1863, p. 838) • " The higher of the two bands * * * is interrupted by a mass of anorthosite or labradorite rock which apparently covers it up. A similar phenomenon appears to occur in Morin (St. Sauveur), where the limit of the labradorite rock * * * immediately flanks the limestone band on the north," and goes on to say : " If, on exploration to the eastward of the Trembling Mountain, it should be farther jiscertained that the two inferior limestone bands of the Grenville series disappear on reaching the margin of the anorthosite, it may be consi- dered as conclusive evidence of the existence in the I^aurentian system of two immense sedimentary formations, the one superimposed uncon- formably on the other, with probably a great difference in time between them." A careful examination of this district in company with Dr. Ells, of Limestunes the Geological Survey, has since shown, however, that one of the sup- "heanortho-^ posed interruptions really is not seen, the anorthosite mass mapped on *>'" at St. the first range of the township of Grandison, and which was probably reported to Sir William by one of his assistants, having no existence, and that the drift is so heavy in this region that even if the other limestone bands did come against the anorthosite the contact could not be observed. A careful examination of the contact on the south-west corner of the area in the neighbourho.id of the village of St. Sauveur, leaves little doubt that the limestone is really cui off by the anor- thosite at this point. The limestone underlies a plain, protruding here and there in large exposures through the drift, whilst the anor- thosite rises from this plain as a steep will or c'iff. The limestone is exposed 200 yards from the foot of the anorthosite wall, but the drift covering then becomes so thick that the character of the contact itself cannot be determined. Both to the east and to the west the associated gneiss is cut off in a similar manner. On the north east side of the anorthosite area there was found, more- At Lakt^ over, another limestone band which runs through Lake Ouareau, and **"»•*""• ! 1 90 .1 QUEBE(!. SectioiiH from .St. .lerrtmf to New OlaHgow. f forms in it a number of small iHlands. It is also well exposed on the south shore of this sheet of water. This bed disappears at the edge of the anorthosite a short distance from the south end of the lake, and no further traces of it are seen until what is probably its continuation appears again interstratitied with the gneiss at the south-eaNt corner of the anorthosite area. In order to understand why Logan regardei;iiirx tinuous throughout the whole district embraced by the map acconi- r,,iiin.ntiHii " panying the present Report, except where it is interrupted by intrusive 'l**", "" '*"''"■ masses of anorthosite. The foliation uf the anorthosite, therefore, being now recognized as a distinctly dynamic phenomenon, and there l)eing no evidence of any series of gneisses except the Grenville series and the fundamental gneiss in the district, this '* Upper Laurentian " series of Logan passes out of existence. Petrography of the Morin Avorthoaite, The earlier geologists who first explored the great stretches of lvtr<>trru|>liy Laurentian rocks underlying various parts of the Doi^inion, in many ',jn,",rJ{""it,.. widely separated disbiicts met with enormous masses of a rock differing entirely from the common orthoclase rocks which make up the greater part of the Laurentian system. This rock was composed principally and sometimes exclusively of plagioclase felspar, but often varied con- siderably in structure from place to place, being sometimes massive, sometimes S(;histose, sometimes coarse and sometimes tine in grain. These rocks they called anorthosite. In the Geology of Canada, Tlie niiinr (p. 22) Sterry Hunt refers to the rock in the following words: "Since """"*"'""•■• all these varying triclinic felspars are anorthic in crystallization, and approach more or less to anorthite in their composition, Delesse thus proposed to designate them by the common name of anorthose, as distinguished from orthose or orthoclase, and the rocks characterized by their presence as anorthosite. In accordance with this we have lulopted the generic name of anorthosite for these rocks." This term anorthosite has often been misunderstood, having been confused with anorthite and supposed to designate a rock consisting of anorthite, a felspar which rarely occurs in these rocks. The word " anorthose " suggested by Delesse, is synonymous with the word pla- gioclase, which has now supplanted it in common usage, and con- sequently the term anorthosite simply means "plagioclase rock," a designation which serves both to define its composition and to emphasize the difference between these anorthosites and the predominating ortho- clase rocks of the rest of the Laurentian region. The place of this anorthosite is in the family of the gabbros, where Comixisitioiii it occupies a position at one extremity of the series corresponding to " ""'"■*""■ that of the pyroxenites at the other extremity. An ordinary gabbro when it becomes very rich in felspar passes into an anorthosite ; when, on the other hand, the felspar decreases in amount, so that the iki Ml ■!■ ";l yi\*i r-4 :!!-; Hlte. I^i :«•! 92 J QUKBEC. H f ^'i pyroxene predominates largely, a pyroxenite results, while if in the case of an olivine gabbro the pyroxene decreases in amount, leaving plagioclase and olivine as the essential constituents, a troctolite results. AlmoHt |)ure Hunt has estimated that three-quarters of the anorthosites of Canada plagioclase. Jq ^qj. contain over five per cent of minerals other than plagioclase. This anorthosite, which occura not only in Canada, but in Norway, Russia and other countries, constitutes a well defined rock type, and one which, not only on account of its peculiar composition, but also owing to the enormous size of the masses in which it occurs and the con- stancy of its character, occupies an important poaltion in the petro- graphical series. The anorthosite of this Morin area exhibits a great variation in structure and colour and in certain places even a considerable variation in composition, but is in mineralogical composition a gabbro or norite free from olivine and very rich in plagioclase. Hand specimens from about fifty different places in the area have been sliced and microscopically < xamined, and the following description of thei^e rocks is based on the results thus obtained. The number of minerals which the rock contains is not large, the variations in composition resulting principally from their irregular distribution. The following minerals have been observed in the rock : — Plagioclase Muscovite and Faragonite Epidote Augite Bastite Zoisite Hypersthene Chlorite Garnet Ilmenite Quartz Zircon '< Orthoclase Magnetite Spinel Hornblende Apatite Biotite Calcite Of these plagioclase, augite, hypersthene and ilmenite are by far the most important. As above mentioned. Hunt adopted the name anorthosite for these Plairioclage "^cks Oil account of the great preponderance in them of plagioclase or anorthose. He considered the type which contains only felspar as the true anorthosite and estimated that three-fourths of the anor- thosites in the Dominion did not contain over five per cent of other minerals.* Like the other constituents of the rock, the plagioclase is quite fresh, showing but very rarely any traces of decomposition, and when it is not granulated (that is protoclastic or cataclastic in structure) presents *T. Sterry Hunt— On Norite or Labradorite Rock, Am. Journ. Sc., Nov., 1809. Minerals (XKiiirring in Morin anorthosite. tile it' in the ount, leaving tolite results. jes of Canada ilajfioclase. t in Norway, type, and one ut also owing and the con- in the petro- ,t variation in able variation jbro or norite Decimens from 1 sliced and of thes-e rocks linerals which ition resulting wing minerals Epidote Zoisite Garnet Zircon Spinel ure by far the osite for these of plagioclase ks only felspar IS of the anor- r cent of other 3 ia quite fresh, iid when it is cture) presents c, Nov., 18««. •1 THE MORIN ANORTIIOSITE. 93 J in hand specimens, almost without exception, a dark violet, but more rarely a reddish colour. This colour is still plainly visible in thin sections, although naturally much fainter, and is seen to be caused by the presence of an immense quantity of minute opaque black rods and extremely small opaque dark points, which give the mineral in thin sections a peculiar turbid appearance. The latter probably represent in part cross-sections of the rods; but are more usually round or slightly elongated individuals of the same substance as the rods and occurring with t'lem. Vogelsang* estimated, in connection with his studies of the anorthosite of Labrador, that these inclusions amount to from one to three per cent of the volume of the mineral, and goes so far as to say : " Le nombre des niicrolites contenus dans fMi'iwte , , inolvwioiHi. un volume determine est susceptible d'etre appr^cie avec plus de precision ; les r^sultats toutefois s'ecarteront beaucoup entre eux, suivant I'echantillon qu'on aura choisi et le point dans lequel on I'aura examine. Dans le labradorite violet figur^ le nombre de micro- lites s'^leve au minimum k 10,000 par millimetre cube; mais pour autres vari^t^s jaunes et gris fone^es le calcul m'a donne un nombre au moins dix fois plus considerable de sorto qu'il y avait ici, dans I'espace born^ d'un centimetre cube plus de cent millions de petits cristaux Strangers." The larger rods are surrounded by a zone of clear felspar. Some inclusions are transparent, and have a reddish- brown colour resembling hicmatite ; these appear in small scales which often show a somewhat distorted hexagonal outline. Objects which closely resemble the above mentioned rods are often seen, when very highly raignified, to be cavities, partly filled up by the dark material of tho rods. These inclusions are pretty uniformly scattered through the felspar individuals, and not confined to certain places, nor pre- sent more abundantly in some places than in others, as is the case with the gabbros described by Williamst or by Judd.J Minute fluid inclusions may often be observed arranged in rows ; in these there appears now and then a moving bubble. In one or two cases small cubes were perceived in them, and in one case it was thought that a double bubble could be recognized. In two or three localities the otherwise normal felspar contained but few of these inclusions, and consequently was almost white in colour. The nature and origin of these dark inclusioi^s, which occur so frequently in the felspar and • Voffelsang— ArchivcK NuerlandaiBe, T. III., 1808. t (J. H. Williams— Galilmt and sHsociated Hornblende Rixsks in the neighbourhood of Baltimore, Md.- Bull. U. S. (Jeol. Suiv. 28, p. 21. :|:J. Judd— Gabbros, Dol'jrites and Baualts of Tertiary age in Scotlatid and Ireland-ti. .T. G. S., 18««, p. 82. «» ■I id Vr Their character. Prof. Judd's examination. i Probably titaiiiferuui 94 J QUEBEC. other constituents of the gabbro, in the most widely separated locali- ties of the globe, have been frequently discussed. The inclusions are so minute that they cannot \ye isolated and chemically examined. Their form is not defined with sufficient sharp- ness and constancy to enable their crystallographic character to be determined. Some investigators have endeavoured to gain some information as to the nature of these minute bodies by observing their deportment when treated with concentrated acids, but the results ob. tained are contradictory. Judd (1. c.) found that they resist concentrated hydrochloric acid. Vogelsang (1. c.) treated a small piece of felspar from Paul's Island, Labrador, which contained them, with hot hydro- chloric acid for four days. He found that the acid had strongly attacked the felspar, but could perceive no alteration in the needles, except that they had become slightly paler. Hagge,* however, found that in the same rock from Labrador all the brown scales were dis- solved when treated with the acid for a time too short to effect a decomposition of the felspar. He considered that they were pro- bably gothite. They are evidently some iron compound, and the peculiar colour of the transparent individuals, taken in connection with the fact that, as will be shown under certain conditions, they unite to form small masses of titanic iron, leads to the belief that the view of Professor Rosenbusch is correct, namely, that they consist principally of titanic iron ore or ilmenite. The transparent ones have the form of the mineral known as micaceous titanic iron ore, which Lattermannf found intergrown with magnetite in the nephelinite of the Katzen- buckel. The peculiar colour of this mineral, moreover, resembles perfectly thnt of these inclusions. The diverse results which the several investigators have obtained in the matter of the solubility of these inclusions may perhaps be explained by the titaniferous iron ore in some hand specimens being richer in titanic acid than in that of others. In this connection it must be mentioned that titanic iron ore is a mineral which is constantly found in these anorthosites in Canada, often in enormous quantities, so that it is considered as particularly characteristic of them, while in the Laurentian proper the iron ores, in the greater number of cases, contain no titanic acid. Lacroix,| * Hagge, Microskopiche Untersuchiing iiber Gabbro and verwandte Geateine, Kiel, 1871, S. 46. t Lattermann in RoHenbusch Mass. Gest, p. 786. tLacroix— Contributions M 'etude des gneiss h Pyroxene, j>. 141— Bull. Soc. Min. France, April, 1839. irated locali- isolated and icient sharp- iracter to be > gain some serving their 16 results ob. concentrated !e of felspar 1 hot hydro- liad strongly I the needles, iwever, found les were dis- irt to effect a ey were pro- iar colour of i fact that, as ) form small of Professor lly of titanic form of the Lattermannf ' the Katzen- er, resembles ts which the the solubility 9 titaniferous a acid than in iron ore is a es in Canada, particularly the iron ores, 1. Lacroix, I I Geateine, Kiel, -Bull. Soc. Min. •DAM*. ] THE MORIX AN0RTH08ITE. 95 .1 who has investigated somewhat similar inclusions in certain Nor- wegian gabbros, which, however, are double refracting, thinks that they are pyroxene, especially as they frequently appear to be grouped together, forming larger grains which may be determined as belonging to this species : "Les grains en question semblent avoir attir^ a eux les particules pyrox^niques en suspension dans le feldspath et les avoir incorporates a leur masse." It is quite possible that these inclu- sions HO often found in gabbros and allied rocks, consist of the heavier minerals of the rock, in some cases pyroxene and in others iron ore, which were finely disseminated through the magma while the rock was crystallizing, or which, perhaps, separated, but as the several constitu- ents crj'stallized. My best thanks are due to Professor Judd for a small collection of thin sections of typical gabbros and peridotites from the north of Scotland, which he has described and on which he has princi- pally established his theory of "schillerisation." An examination of S^hilleriHa tUese revealed the fact that nowhere in them are the inclusions in the plagioclase so numerous and well defined as in the Canadian anortho- sites. The peculiar arrangement of these inclusions in the Scottish rocks along cracks, fissures, i*i:c., which Professor Judd has described, and which especially supports his theory of their secondary origin, is not observed in these Canadian rocks. Their inclusions are on the contrary distributed thickly and pretty uniformly through the whole felspar individual, generally indeed throughout the felspar of the whole rock. They disappear, as above mentioned, only when it has been granulated. This remarkable fact will be referred to again. The uniform distribution of these inclusions does not prove that they are not schillerization products, for if the rock were com- "pletely schillerized these products might be quite evenly distributed in it. Only in a few places in this Morin area does the plagioclase exhibit that play of colours which is produced by these inclusions in the felspar from Labrador and elsewhere. The plagioclase i% almost invariably excellently twinned, according to both the albite and pericline laws, the two sets of twin lamellic crossing one another at right angles in the thin sections. This twinning is apparently sometimes secondary and produced by pressure, as for instance when the lamella; appear along a certain line or crack, or when they appear in places where the plagioclase individual is twisted. In most cases, however, they are of primary origin. Frequently in Twinning the sections there are a few untwinned individuals of plagioclase which l*laKiocI»«e. are probably cut parallel to oo P S (010). But in certain hand- specimens there is a considerable percentage of untwinned felspar. :f ii«r '^;i ■'. i!h 1 "\V- \m \m 96 J QUEBEC. Ci)iii|K)8ition of the plagioclase. W r I I resembling in all other respects the plagioclase which shows a well de- fined twin structure. In order to determine whether in these cases two felspars were really present, separations by means of heavy solutions were made, on material from three hantl specimens from different local- ities, in the thin sections of which these untwinned felspars occurred in considerable quantity. Since, however, in a solution having a specific gravity of 2 ' 67 all the constituents sank, these untwinned individuals cannot be more acid than labradorite, to which variety the remaining felspar likewise belongs. Similar occurrences of untwinned plagio- clase have been often observed. Hawes*, who investigated some of them, gives an analysisf of an ordinary specimen of typical labradorite of St. Paul's Island and adds : " Some of the anorthosites described by T. Sterry Hunt in the Geology of Canada, 1865, were proved by his analyses to be composed of pure labradorite, and some sections of the same which he submitted me for examination were found to be com- posed of a multitude of small grains, none of which were twinned." An examination was made of the well twinned plagioclase from two other localities. The first was a hand specimen of a typical anorthosite which is found five miles north-west of Ste. Adele in the Morin dis- trict. Its specific gravity was between 2'65 and 2'67, and it had, therefore, also the composition of an acid labradorite, a fact confirmed by the values of the extinction-angle measured on a small fragment separated by means of Thoulet's solution. The second was from the village of Ste. Adele itself, which lies at the corner of the Morin area. Here the anorthosite is porphyritically developed with large plagioclase crystals which are sometimes as much as four inches long. These had the following extinction angles: on o»Po> (010) 24Jr° to 26", on O P (001) = 6°. An analysis of the bluish opalescent plagioclase from the Morin district will be found in the table of analyses given on page 130 .i ; here again the felspar is a labradorite. The plagioclase of the anorthosite from these six different localities is, therefore, in all cases labradorite, and there is every reason to believe that the felspar throughout the whole area belongs to this variety. Although it is generally quite fresh, yet a partial decomposi- tion was observed in one or two cases, where it is altered to a mixture of calcite, epidote and zoisite, as mentioned in the description of these minerals. A peculiar variety of the rock, having a saussuritic habitus, was observed at New Glasgow. This is an entirely local • Hawes— On the detenniiiatiun of FeUiiar in thin HttctionH of RocIch. Mu8., Washington, 1881, p. 134. t See table of analyses, p. 130.1. Proc. Nat •] THE MORIN ANORTHOSITE. 97 J '8 a well de- >8e cases two vy solutions Berent local- ir» occurred inga specific 1 individuals le remaining nned plagio- ited some of il labradorite described by iroved by his ictions of the 1 to be com- twinned." lase from two 111 anorthosite he Morin dis- 7, and it had, tact confirmed nail fragment was from the le Morin area, rge plagioclase These had o 26, on O P clase from the mpage 130.1 ; ■rent localities )ry reason to elongs to this ial decomposi- i to a mixture description of a saussuritic entirely local )ckH. Proc. Nat occurrence connected with the small zones of disturbance which here run through the anorthosite. In thin sections of this rock, which is almost entirely composed of plagioclase, mixed only with a few small Alteration grains of iron ore, the plagioclase is seen to have undergone a peculiar '"^ "° ' alteration. The alteration product is a mineral usually having a iibrous structure, and occurs in the plagioclase in little spots. It has the optical character of a bastite or pseudophite, and the decomposed felspar resembles, therefore, to a certain extent that of Waldheim in Saxony, described as pyknotrope by Breithaupt. In another hand specimen of the same rock from New Glasgow, the felspar is changed into a colourless mineral which forms small feather-like clusters. It shows magnificent polarization-colours and has a distinct cleavage to which the extinction is parallel. The mineral possesses the optical properties of muscovite but may be paragonite, whicli cannot be dis- tinguished from muscovite under the microscope, and is a more probable ' alteration product of plagioclase. The augite is, with a few exceptions, generally present in much Augite. smaller quantity than the plagioclase, but is next to it the most abundant constituent. Rhombic pyroxene is present, however, in nearly, if not quite equal amount. The augite occurs in irregularly shaped grains of a light-green colour, which are either non-pleochroic or exhibit a scarcely perceptible pleochroism in greenish tints. In sections which are nearly parallel to the base, the typical cleavages characteristic of pyroxene are seen cutting each other almost at right ' angles. They are often intersected by a third more perfect cleavage which is parallel to oo P oo (100) as shown by its position relative to the plane of the optical axes. In the prismatic zone the mineral shows an extinction-angle from 0° to 45°. In many sections of the pyroxene, there are brownish-black tables or small black rods which resemble very much the inclusions in the plagioclase, above described. Where these occur they are frequently parallel to oo P 6o (100) ; in other cases instead of being scattered throughout the whole individual they are confined to certain spots. The augite can often be observed to have grown around grains of iron ore. It is generally quite fresh, but in many hand specimens is decomposed. The products of decomposition consist sometimes of a finely granular mixture of chlorite, and a rhombohedral carbonate with occasional quartz grains, the whole constituting a gray almost opaque mass. In other specimens, the augite is changed into a yel- lowish bastite, which then fills up not only the space originally occu- pied by the augite, but also penetrates into the small fissures of the 7 % i:.r Is,*; I ■ :!i 1:1 I;! If 98 J QUEBEC. Rhombic pyroxene. Hypursthene. rock and forms thread-like veins and scales even in the felspar grains. In some specimens again it is converted into a mineral resembling set-pentine. When both pyroxenes occur together in the rock, the augite is generally intimately associated with the rhombic pyroxene. The rhombic pyroxene, which occurs so often in association with the augite, does not essentially diifer from the latter as far as can be ascer- tained from its thin sections, either in index of refraction, in double refraction or in colour. It is however strongly pleochroic with the following colours : a = red, b = yellowish green, c = green. The absorption is (l > b > C, the difference between a and f) being very small. Its rhombic character, was established by the following observations in the case of a hand specimen from the township of Chilton, in which the mineral occurred in fresh condition and in larger quantity than usual. Sections parallel to the base showed the two cleavages of tlie prism which intersected almost at right angles, as well as a third more perfect set of cleavages, to which small black rods were often parallel. Since the direction of the extinction was also parallel to this latter cleavage, it must be in the direction of a pinacoid. In convergent light, there was seen on the basal section a bisectrix, but not an optic axis as n the case of a monoclinic pyroxene. When a section in which an optic axis appears was examined, the above-mentioned pinacoidal cleavage was found to be parallel to the plane of the optic axes. The pinacoid in question was therefore oo P d8, that is to say it cuts off the acute prismatic angle as oo P ob does in the case of diallage. In sections which showed an optic axis and only one set of cleavages to which the small rods lay parallel, the cleavage was seen to be parallel to the plane of the optic axes. In all sections which contain the mineral, many grains are found which show only one good cleavage to which the extinction is parallel. In general it is like the augite quite fresh, in a few sections it appears, however, changed into bastite, and in a few others into a serpentine-like mineral. It sometimes contains the dark scales and rods so often found in hypersthene, but very often these are entirely absent. It is indeed a remarkable fact that in these Canadian rocks, the iron-magnesia minerals contain but a few of these inclusions, while the associated felspar is filled with them, the exact opposite being true in the case of the gabbros and associated rocks of the Scottish Highlands, which have been described by Prof. Judd. ilspar grains. I resembling he roclc, the I pyroxene. tion with the can be ascer- on, in double 'oic with the and b being r observations ilton, in whicli quantity than savages of the s a third more often parallel. to this latter nvergent light, *n optic axis as which an optic oidal cleavage !'he pinacoid in off the acute In sections >s to which the lei to the plane rains are found tion is parallel. few sections it others into a ark scales and ise are entirely !anadian rocks, lese inclusions, exact opposite jd rocks of the Judd. ■] THE MOKIN AN0RTH08ITR. 99 .T Hornblende does not occur in the anorthosite of Morin, except in a Hornblende few places near the contact with the gneiss. In these cases it ii always found in intimate association with the pyroxenes, in the form i I irregu- larly defined grains generally about the border of the granulatn 1 masses of the pyroxene. It occurs as a general rule only in very small quantity. It is usually green in colour, but is often brown. It shows the cleav- ages, the small extinction angle, and the characteristic pleochroism of the species. In a hand specimen from the neighbourhood of the con- tact on Lake I'Achigan, the maximum extinction-angle was found to >^ be 15° and the following pleochroism was observed : a = greenish yellow, i) = yellowish green, c = green. The absorption was C > t > fl- In another hand specimen, (juite close to the contact, about six miles north of New Glasgow, a brown hornblende was likewise found in small amount. The extinction-angle was 18', with the following pleochroism : a = light brownish yellow, {) = deep brown, f = deep brown, with the absorption as before, C > ft > fl- it also occurs in the peculiar rock which has been referred to above as a gabbro, which was found in a number of places between the true anorthosite and the gneiss. Biotite never occurs in large amount, but is present rather Biotite. frequently in very small amount as an accessary constituent. It is usually found with the iron ore or with the hypersthene, and shows characteristic brown colour, strong pleochroism and parallel extinction. The occurrence of muscovite or paragonite has been referred to in Muscovite or describing the plagioclase. paragonite Chlorite occurs occasionally in small quantity as a decomposition chlorite, product of pyroxene or biotite. It is doubtful whether quartz ever occurs in the anorthosite as Quart/., a primary constituent. It occurs, however, in small amount in the form of little grains scattered through the anorthosite on lot 36 of range VI. of the township of Wolfe, near the contact of the anorthosite with the surrounding gntiss. Again on the west side of the Achigan River, near New Glasgow, it ?s occasionally found in the anorthosite, and has the appearance of a primary constituent. Here again, how- ever, the occurrence is near the contact with the gneiss, and it is certain that some secondary quartz is present as a decomposition pro- :! ) ; ' 100 J QURUEC. duct of the pyroxene, so that the quartz which has the appearance of a primary constituent may also be of secondary origin. In the gabbro which occurs as above stated in many places between the typical anorthosite and the gneiss, quartz is quite frequent. I'.iit in this rock many facts point to the secondary origin of the quartz. It often occurs, for instance, in more or less sharply defined veins, made up of large individuals. When it occurs in the form of separate irregular grains, those extinguish uniformly, although they are often riore or less fissured, but they are by no means so much broken as might be expected if they were primary ingredients in view of the extremely broken condition of the felspar and the other constituents of the rock. Ilmenite and I" nearly every section of anorthosite, some irregularly shaped grains magnetite. q{ j^ opaque black iron ore are seen. These are usually few in number. The quantity of iron ore is considerable only in a few places, and as in these the percentage of pyroxene increases in the same proportion, the rock here assumes a very dark colour, so that it is often taken for an iron ore. These portions of the anorthosite rich in iron ores are only few and local, and they pass over into the normal gabbro of the area. which, as above mentioned, is very poor in iron ore. If these iron ore grains are examined by reflected light, they are found to be black, and in a few cases they can be seen to be partly changed into a gray decomposition product, evidently a variety of leucoxene. This circumstance proves that the mineral contains titanic acid in con- siderable amount. In three hand specimens from widely separated parts of the area, an intermingling of two iron ores was distinctly seen. In that from the township of Wexford, lot 7, range I., one of the above-mentioned locali- ties where the anorthosite is rich in iron ore (Section No. 398), careful observation in reflected li<>ht showed the iron ore to occur partly as a bluish-black coarse-grained variety, and partly as a brownish black finely granular variety, both l^eing irregularly intermingled and dis- tinguishable only by reflected light. When the section was treated for about half an hour on a water-bath with warm concentrated hydrochloric acid, the coarsely granular variety was entirely dissolved and the acid became strongly coloured with iron, while the finely granular variety was apparently not at all affected. There is here evidently an intergrowth of magnetite with ilmenite or at least with a titaniferous iron ore. the appearance uf n. ly places between te frequent. litit 1 of the quartz. It jtined veins, made form of separate gh tliey are often ) much broken us 8 in view of the other constituents larly shaped grains illy few in number, w places, and as in me proportion, t)ie often taken for an I iron ores are only jabbro of the area. ight, they are found be partly changed riety of leucoxene. titanic acid in con- »art8 of the area, an In that from the ve-mentioned locali- jn No. 398), careful to occur partly as a a brownish black «rniingled and dis- lour on a water-bath coarsely granular le strongly coloured pparently not at all of magnetite with *aAM«. ] THR MORIN AN0RTH08ITE. 101 J In another hand specimen (from the neighbourhood of Lake Ouareau) a similar intergrowth was observed ; the grains had a bivndod appearance in reflected light, one variety crossing the other in a single or double set of interrupted bands. When the section was treated with cold concentrated hydrochloric acid for 48 hours, no efl'eot was produced ; but when treated with warm concentrated acid in a water-bath, one variety of iron ore was dissolved as before, while the other again remained undissolved. In this case the intergrowth is probably parallel to the face of an octahedron or rhombohedron. A similar InteMrrowth intergrowth has been described in the iron ore of the Carrock Fell iron ores, gabbro, and in the nephelinite of the Katzenbuckel,* except that in the latter case, the titanic iron ore occurs in the form of micaceous titanic iron ore, not as the coarse and opaque variety found in the above-mentioned rocks. It has been the invariable experience in Canada, that the large iron ore deposits common in these anorthosite rocks, contain so much titanic acid, that it has been imimssible hitlierto to work them profitably. Recent experiments, however, lead to the hope that in the future some of them at least may be smelted with profit. (Appendix II.) In order to determine whether the iron ore which is disseminated in small grains throughout the whole rock was also rich in titanic acid, the iron ore of three hand specimens of the anorthosite from different parts of the area was separated and tested. In every case the mineral was but faintly magnetic and gave a strong titanic acid reaction. Two specimens of iron ore from the pegmatite veins, which cut Titanium in through the anorthosite and the gneiss at the contact of the two form- a^orthositex atioiis, west of Ht. Faustin, and therefore do not belong to the anortho- site, showed strong magnetism and gave only a faint reaction for titanic acid. The iron ore bed, a short distance west of St. J^rdme, in the orthoclase gneiss, also consists of magnetite and contains no titanic acid. We therefore find that these investigations confirm the conclusion that the iron ore of the anorthosite is very rich in titanic acid, while the iron ore of the Laurentian gneiss generally contains no notable quantity of this substance. In the variety of anorthosite very rich in iron ore from lot 7, range j^n ores ot I., of Wexford, the evidence obtained from the thin sections, shows srne'Mes ' usually free that the iron ore crystallized later than the pyroxene, as it can be from observed frequently completely inclosing individuals of this mineral. The same fact was noted in the case of the pyroxene granulites. (See page 79 j). * Lattennan, in Rosenbusch, Physiographie der Massigen (Jesteine, p. 786. titanium. t ti H: I - 'I i • (: Pyrite. Apatite. Calcite. Epidote. Garnet. Zircon. 102 J QURBEO. A few small grains of pyrite often occur in the thin sections of the anorthosite. They are generally found associated with the iron ore. Apatite is seldom observed in the anorthosite. When it does occur it is in the form of more or less rounded grains. It is more frequently found in the varieties rich in iron ore in the township of Wexford and other localities, than in the normal anorthosite. Calcite was found in but two hand specimens. One of these wa.s fresh, and contained a small amount of calcite which might pos- sibly be a primary constituent. The other was from New Gla-sgow, and in this the calcite appears together with zoisite, epidote, etc., as a decomposition product of the plagioclase. The only locality where epidote occurs is also near the village of New (irlasgow. It is found in several sections of the anorthosite from this place, along with chlorite and quartz, as a product of the alteration of the pyroxene, and as above mentioned with calcite and zoisite as a product of alteration of the plagioclase. In one or two places it also occurs in small bands, cutting diagonally across the anorthosite, following the line of small faults. The epidote is everywhere secon- dary. Garnet does not occur as a constituent of the normal anorthosite, but is often found near its contact with the surrounding gneiss. It has a pinkish colour, and is seen under the microscope in small irregular masses, which are often mixed with or completely surround tlio grains of iron ore. In the sections of the variety of anorthosite rich in iron ore from the township of Wexford, lot 7, range I. (and from other places above mentioned), a pale-pink garnet occurs forming a small zone of uniform breadth around every grain of iron ore or pyroxene where these would otherwise come in contact with the plagio- clase. Between the pyroxene and the iron ore there is however no garnet. It is quite isotropic and has grown out from the iron ore or pyroxene into the felspar, against which it is bounded by shfirp crys- talline outlines. These zones of garnet are analogous to the zones of actinolite and hypersthene around the olivine of the anorthosite from the So,uenay River, and those which have also been described in oliviiie gabbros of many other localities. Zircon is not found in the normal anorthosite, but it occasionally occurs in this rock near its contact with the gneiss. It is seen only in small quantity, and especially in the peculiar contact variety which occurs, as above mentioned, in some places between the anortho- site and the gneiss. It was observed in this in many localities. It ] THE MORIN AN0RTII08ITB. 103 J has the form of small stout prisms, always with more or less rounded edges, which are characterized liy a parallel extinction, high refractive index and strong double refraction. Spinel was obberved in a single hand specimen, in the form of suiall Spinel, rounded isotropic grains, deep green in colour, occurring as inclusions in plagioclase and pyroxene. The Structure 0/ the Marin Anort/wsite. The macroscopic structure of these anorthosites, as well as that of most structure of of the crystalline rocks forming the Laurentian system, is best studied ^1°"" on the great glaciated surfaces of the roches moutr;nndes, which protrude through the drift in all directions. On a freshly fractured surface, or even on a smoothly glaciate i surface which has been pro- tected from the weather, comparatively little of the structure may be Hcen ; but when the glaciated surface has been exposed, during the interval which has elapsed since the disappearance of the ice, to the etching action of the weather and the dilute solution of carbonic acid known as rain water, the structure of the rock is brought out in a wonderfully clear and striking manner, just as the structure of wrought iroil or of various alloys is brought out by the treatment of their pol- ished surfaces with the stronger acids. Such weathered surfaces, moreover, being many square yards in extent, enable the structure of considerable masses of the rock to be determined and the relations of different structures to one another to be clearly seen. If any large weathered surface of the anorthositc, such as is found Glaciated in the roches moutonnees anywhere within the Morin area, be *"' *"**• examined (leaving out of consideration for the present the arm-like extension and tluit part of the main area adjoining it), it will be noticed that the rock, which is coarse-grained and of a deep violet colour, has not that regularity of structure which we see in a typical granite, but presents a more or less irregular structure. This irregu- larity is sometimes scarct^ly noticeable, but is at other times striking, and is due to the presence of the bisilicates and iron ore in larger amount in some parts of the rock than in other parts. The portions richer in bisilicates may take the form of large irregular-shaped patches occurring at intervals through the rock, or of many small patches occurring abundantly in certain parts of the rock which else- where is nearly free from them. In some cases these are arranged structure so as to form irregular wavy streaks instead of patches, which sometimes take a rudely parallel direction, giving a sort of strike to the rock, but which in other places are quite irregular in I '4 Hi ii\ u 11 Variation in relative amount of OonHtitiientH 104 J QUEHKC. arrungement. Between these patches or Htreaki rich in bUilicntei, and rather badly detined against them, are portionH of the rock which are very j)(x>r in or often quite free from biflilicates. The structure is well represented in Plate VI., which is a photograph of a large anorthosite boulder on lot 5 of the ninth range of Chertsey. Here the iron ore and bisilicates are aggregated together in irregular-slmpeil more or less rounded portions of the rock, while the remainder of the rock is almost absolutely free from iron-magnesia constituents. Of these portions containing the bisilicates and iron ore, these constituents form about one-third of the rock, the rest being plagioclase. Large individuals of plagioclase, irregular in shape ami which will be referred to again, occur quite abundantly in the parts of the rock free from bisilicates, but are very rarely found in the patches containing the bisilicates. With the exception of the larger individuals of plagio- clase, the rock is uniform in grain throughout. The portions contain- ing the bisilicates weather more readily than the rest of the rock, and thus leave hollows on the weathered surfaces, while when the patchcM are elongated, as is usually the case, irregular sausage-shaped cavities result. In the occurrence represented on Plate VI. it will Ije noticed that one of the masses rich in bisilicates and much larger than the othei's, forms a rude band across the lower portion of the Imulder. In such coses, the bisilicate individuals are arranged with their larger axes in a direction rudely parallel to the band. Often in connection with this irregularity in the relative proportion of the several constituents present in the rock, but often quite inde- pendent of it, there is a rapid and frequently abrupt variation in size of grain from place to place, certain spots or streaks being, as before, Hner or coarser than the mass of the rock. More ur less well pronounced irregularities, due to one or both of the causes alxjvp mentioned, are met with in all the anorthosite areas of Canada which have been examined, but are not peculiar to them, being found in gabbros and allied basic piutonic rocks in various other parts of the worhl. Thus Dr. Geoigj H. Williams in his paper entitled The Gabbros and Asso- ciated Hornblende Rocks occurring in the neighbourhood of Baltimore, Md., says on page 25 : " The most striking feature in the texture of the unaltered gabbro is the repeated and abrupt change in the coarse- ness of the grain which is seen at some localities. It was undoubtedly caused by some irregularity in the cooling of the original magma from a molten state, for which it is now difficult to find a satisfactory explanation. The coarsest grained varieties of the Baltimore gabbro occur in the neighbourhood of Wetheredville and there these sudden changes in texture are most apparent. Irregular patches of the coarsest 1 bisilicntes, ) ruck which structure ia of a large •tsey. Here gulnr-ahiiped iinder of the /ituentH. Of constituentd ilftse. Large U be referred ck free from ntaining the iIr of plagio- /ions contain- bhe rock, and ti the patcheH aped cavities ill 1)6 noticed ger than the I Imulder. In their larger ve proportion en quite inde- ntion in she of a liefore, Kner II pronounced lentioned, are ih have been gabbroH and world. Thus rod and Asao- of Baltimore, ;he texture of in the coarse - I undoubtedly magma from satisfactory limore gabbro these sudden )f the coarsest 'f, lb o 9: ] THE HORIN ANORTH08ITE. 105 J kinds lie embedded in those of the finest grain without any regard to order. In other cases a more or less pronounced banded structure is produced by an alteration of layers of different grain or by such as have one constituent developed more abundantly than the others. Such bands, are not, however, parallel, but vary considerably in direc- tion and show a tendency to merge into one another as though they had been produced by a motion in a liquid or plastic mass."* Similar coarse-grained patches are sometimes seen in the gabbro Similar or o elsewhere. diorite quarried at Kiihlengrund, near Eberstadt, in Hessen, in a rock which is otherwise perfectly massive and pretty regular in grain. Other similar cases might be cited. One of the most remarkable occurrences, and one especially note- worthy as showing how a transition takes place from a perfectly normal and massive rock, through one in which these irregular coarse-grained patches are developed, into one showing an imperfect banding such as is sometimes seen in anorthosite, was observed in the great Saguenay anorthosite area, along the course of the River Shipshaw, which runs River into the Saguenay from the north about seven miles above the Shipshaw. town of Chicoutimi. Along the stream there are at frequent intervals immense smooth roche moutonn^e exposures of anorthosite, etched by the weather and burnt clear of all vegetation by forest fires, thus presenting excellent surfaces for the study of the rock. The series of exposures in question is bounded on the north by a great dyke of gabbro, about a half a mile wide, which cuts across the anorthosite, and extends down the Shipshaw a distance of eight miles in a straight line to a point three miles from its union with the River Saguenay. At the first-mentioned point the rock is coarse-grained, absolutely massive over large exposures and regular in grain. This continues for about half a mile, when ill defined patches which are very coarse in grain appear in the rock. In the coarse-grained portions the indivi- duals composing the rock measure an inch or even more across, while in the mass of the rock they are much smaller. Both show a well mai-ked ophitic or diabase structure, in which the plagioclase occurs in lath-shaped individuals, the augite filling in the intervening spaces, a Change in structure which is occasionally seen, but is very unusual, in the anor- * '"" ^^^^' thosite. This continues for rather over four miles, with in places a further irregularity due to a great variation in the amount of the several constituents present in different parts of the rock, the rock over considerable exposures being all plagioclase, while elsewhere it is m •(J. H. WJlliamH, Bulletin No. 28, U. 8. «eol. Survey. ,*^1 m 106 J QUEBEC. Streaked or banded rocktt (.Tranulatiun of constituents. rich in diallage, which sometimes occurs in masses as much as a foot and a half in diameter. Large masses of almost pure plagioclase or diallage are thus found in the rock. After an interval of a mile, where the rock is concealed, there is another series of exposures, extending over a mile along the river, in which, as before, the ophitic structure is well developed, but in which the rock is irregularly streaked or banded owing to the fact that the want of uniformity in grain and composition, described above, is no longer displayed in the shape of irregular patches, these having been pulled out into long wavy streaks, similar to those described above by Dr. Williams. Further down the river these streaks begin to assume a rudely parallel direction, giving the rock a determinable strike, while the ophitic structure gradually disappears. A case is thus pre- sented, where an undoubtedly eruptive rock, (juite massive and with well pronounced ophitic structure, gradually passes over into one which is banded, the bands being marked by great variations in size of grain and in relative proportions of constituents ; and it thus becomes evident, that the rude banding which is a common structure in certain anorthosite areas, and which was formerly supposed to represent a more or less obliterated stratification, is really a structure developed by movements in a truly igneous and massive rock. But another structure is also presented by the anorthosites. When any of the anorthosites in the area embraced by the present report are carefully examined, this streaked or irregularly banded structure is seen to be accompanied in most, if not in all cases, by a peculiar break- ing or granulation of the constituent minerals of the rock. This is often beautifully displaced by the large weathered surfaces. Tiie accompanying sketch (Figure 9), taken from an exposure in the Morin area near Ste. Marguerite, shows the appearance presented in one of these cases. Here the banding is distinct, but in many parts of the area, even where no banding is seen, the roek presents this peculiar brecciated structure, fragments of plagioclase and of other constituents of the rock being imbedded in a .species of groundmass made up of smaller grains. As plagioclase in most cases preponderates almost to the exclusion of the other constituents, the fragments are usually of this mineral, and, although occasionally showing an approximation to good crystalline form, they are almost invariably quite irregular in shape, often possessing absolutely tattered outlines. The groundmass of smaller grains also consists of plagioclase. In some places these fragments constitute the greater part of the rock ; elsewhere they are present very sparingly and the groundmass preponderates. The larger individuals can, moreover, be frequently seen in the very act of >. 1 THE HORIN AN0RTH08ITE. 107 J uch as a foot )lagioclase or aled, there is the river, in but in which fact that the above, is no having been ibed above by gin to assume inable strike) se is thus pre- live and with nto one which I size of grain thus becomes ,ure in certain bo represent a ure developed asites. When ient report are 1 structure is peculiar break - rock. This is surfaces. The e in tiie Morin jnted in one of Y parts of the s this peculiar ,er constituents IS made up of rates ahnost to are usually of iproximation to be irregular in he groundmass >e places these elsewhere they nderates. The the veiy act of breaking up, the several fragments having shifted their position but very slightly ; and in such cases it is often evident that the breaking is not of the nature of a simple crushing, for from the same individual pieces will be found breaking oflf in various directions quite at haphazard. V Figure 9.— AnortlioBite showing a brecciated st.acture, near Ste. Marguerite, Town- ship of Wexford. Fragments of Vlagioclase and Hyi)er8thene in a groundmass of the same minerals in a granulated condition. The sketch represents a width of 9 feet. • ... When examined under the microscope in thin sections, hardly a Microscopical specimen of any coarse-grained variety can be obtained from any part character. of the area which does not show at least traces of this clastic or granulated structure ; and if a series of specimens is studied, every step can be traced in the passage from the massive rock, showing the merest traces of this structure throygh intermediate breccia-like stages, to anorthosite .consisting entirely of broken grains, perhaps with mere remnants of the original large individuals. The three accompanying micro-photographs illustrate successive stages in this granulatitn. (Plate VII.) They are taken from three thin sections of anorthosite from different parts of the Morin area, photographed in polarized light between crossed nicols and equally magnified, the enlargement in each case being 22 diameters. (A.) This section, from the large exposures about five miles north- Photographs west of the village of Ste. Adele, in the township of Morin, before sections of anorthosite. 108 J QUEBEC. Show 8tage8 of (granula- tion. referred to (p. 96 J), represents the massive anorthosite, showing only the merest traces of granulption on the left of the field. The size and shape of the constituent individuals of plagioclase and their polysynthetic twinning are well seen. The rock is composed almost exclusively of this mineral, the individuals of which are neither bent nor twisted, and no strain shadows are to be observed. (B.) In this section, which was prepared from a specimen collected about three and a half miles north-east of White Lake, in the front of the township of Chilton, a distinct breaking or granulation of the plagioclase can be observed, especially in the lower portion of the slide, while the same process can be elsewhere seen, though less well marked. The large plagioclase individuals no longer meet along clear well defined boundary lines, but are irregular in sliape, cracked, and separated from one another by a mosaic of broken grains. Strain- shadows, twisted twin lamelhe and other evidences of pressure are well shown. The rock shows no distinct foliation or banding. (C.) The third section shows the appearance presented by a highly granulated variety of the anorthosite under the microscope. This specimen was obtained from the arm-like extension of the anorthosite mass before mentioned, near its western contact with the gneiss, on range XI. of the township of Rawdon. In this section, about one- half of the field is occupied by broken grains of plagioclase, while in the middle is a large plagioclase individual in process of destruction. A line of granulated material is being developed in a longitudinal direction through the large crystal, making, as is usual, an angle of about 20' with the lines of twinning, and which would, if continued, cut it in two ; while about its edge little fragments of the plagioclase can be seen in the very act of breaking off — first a strain-shadow (excellently seen on the upper edge of the large individual) appearing, then a curved crack extending in from the edge of the crystal, and finally the breaking away of a small piece of the mineral, leaving an irregular indentation. The appearance is precisely that which the mineral would present if by means of a pair of small pincers little pieces were being broken off the edge. The strain having been re- lieved by fracture, all evidence of pressure disappears in the broken grain. And if a thin section were composed of broken grains alone, it would in most cases be impossible to determine that these had resulted from the breaking down of larger individuals. This rock is ex- cellently foliated, owing to the finely granulated material, resulting from the breaking up of each large individual, arranging itself in the shape of a very flat lens about the crystal remnaiit from which it (ii-.in.iKJK'.M. SiiivKV OK Canada. Vol.. vin., I'AUT J. FiGt'KK A. FlUURK H FrouHE O. I'l MK VII - MICK0I'H()T(M;KAPHS, showing the PRO(iRESSlVE (iKAXULATU)N OF THEMORIX ANORTHOSITE UNDER THE INFLUENCE OF PRESSURE. X 22. ^» f ] THE HORIN AN0RTII08ITE. 109 J was derived, which lens, of course, lies in a plane at right angles to the pressure, and in section appears as a long slender tail of broken grains extending from the remnant in either direction. (Fig. 10.) The pyroxenes, rhombic or monoclinic, when present in the rock, undergo a precisely similar process of granulation with the formation of similar tails of broken grains. Figure 10. Sometimes large individuals can be observed which have broken into two or more pieces during the process of granulation, the lens of broken grains thus inclosing several fragments more or less separated from one another, which from their respective outlines can be seen to have been originally one. (Fig. 10.) A very remarkable fact in, this connection, which has already been piagiociaae briefly referred to in describing the mineralogical composition of the changes colour anorthosite, is that the large crystal fragments of plagioclase have a granulated. deep violet colour, while the granulated plagioclase is white. This contrast is excellently seen either on the weathered surface (Plate VIII.) or when a thin section is placed on a sheet of white paper, and is due to the fact that the minute dark-coloured or black inclusions, which abound in the large individuals, are absent in the broken material. They seem to have aggregated themselves together into little grains of titanic iron ore, which occur in the granulated plagio- clase, but which on the other hand are absent in the large individuals.' So distinctive is this contrast of colour, that when a thin section con- s taining plagioclase in both forms is placed under the microscope, it is possible at once co predict from the colour alone, just what portions will show granulation and what portions will not, before the actual structure has been revealed by the agency of polarized light. This might seem at first sight to indicate a recrystallization in the case of the granulated portions of the plagioclase, but the facts do not seem to support this supposition. The felspar, during the process of granu- lation, does not at any rate alter in composition, but merely breaks, and through the loss of the dark inclusions becomes lighter in colour. No investigations bearing on this particular point have been made on the anorthosite of the Morin area, but the fact has been established no J QUEIiEC. No change in coni|iogition of the plagrioclaso wHmi granulated. White anorthosite. Granulated varieties on Hides of intrusion. by the study of precisely similar anorfchosites from several other areas. Thus it was found in the case of the anorthosite of Mount Williams, on the River 8hipshaw, in the Saguenay area, that the large dark- coloured individuals and the white granulated plagioclase, were l)oth labradorite, differing in specific gravity by only 015, the dark felspar being naturally a trifle heavier on account of the inclusions. Again, in analyses XIV., XV., XVI. (see p. 130 .1) are given the results of an examination by Dr. Sterry Hunt, of the large plagioclase individuals and the finely granulated base of an anorthosite from the Chateau Richer area. Both are in this cat^e more acid, approaching andesine in composition; but here again in composition they are identical. The same circumstance lias been confirmed by Leeds in the case of the anorthosite of Essex County, New York, and by Sachsse in a flasergabbro from Rosswein in Saxony*, although in these two latter cases the material analyzed was not quite pure. Frequently, as has been stated, the production of the granulated material from the large individuals can be actually observed ; and in such cases it can be seen that so soon as the fragment is separated from the large individual its colour disappears. The granulation, it would appear, in some way gives freer play to the forces which bring about the concentration of the material of the dark inclusions. When the anorthosite is composed entirely of the finely granular material, if it be almost entirely plagiocliise as is usually the case, the rock can hardly be distinguished, especially on the weathered surface, from a white crystalline limestone. This peculiar variety of white granular anorthosite, with comparatively few of the large individuals remaining, is also largely developed in the Saguenay and other of the anorthosite areas in the province of Quebec, and is described from the area in Essex County, New York, by Leeds, and from Labrador, by Vogelsang, as well as by other observers, it being found apparently to some extent, in most of the localities where anorthosite is largely developed. In the Morin anorthosite, and the same is true of the Saguenay area, the most granulated varieties are found near the sides of the intrusion, especially on the east side, as if the pressure had been exerted from that direction, but more or less distinct evidences of granulation can be seen throughout the entire area. The white granulated anorthosite forms the greater part of the arm-like extension of the Morin mass. * Ueber den Feldspathgemengtheil des Flasergabbros von Rosswein i. S.— -Ber. d. naturf. Ges. i. Leipzig, 1883. other areaa. nt Williams, large dark- e, were l)oth dark felspar >ns. Again, results of an ! individuals the Chateau ng andesine re identical. the case of Sachsse in a se two latter 3 granulated rved ; and in parated from ion, it would bring about When the terial, if it be k can hardly rom a white omparatively eloped in the ce of Quebec, rk, by Leeds, observers, it ;alitie8 where iguenay area, bhe intrusion, exerted from Illation can be i anorthosite Morin mass, in i. S.— Ber. d. (iEoLOdlCAL SlIKVRY OV CANADA. Vol.. VIII., Part .T. m Platb VIIl.-(iRANULATKD ANORTHOSITE, WITH INCLUDED REMNANTS OF THE ORIGINAL ROCK, RIVIERE AUX SABLES, TOWN.SHIP OF JONc^UlfeRE, QUE. (itEDL'CED O.NK-HALF.) ] THE MORIN ANOHTIIOHITK. Ill J protruding through the drift in all directions in the form of hundred of smooth white hummocks giving a striking appearance to the lands- cape, as for instance, about the village of New Glasgow ; and this district being easily accessible by roads and railways, the structure and character of the rock can here be studied with couiparutive ease. Further, it can be observed that everywhere in this arm-like extension and in almost all its occurrences elsewhere, this white granulated auorthosite is more or less distinctly foliated, owing to the arrange- ment of the bisilicates and iron ores in more or less distinctly parallel Ii-i>s or streaks. It is often quite evident that these are nothing tiii^ro than the rounded patches, rich in bisilicates, described on p. 104 J, as occurring in the massive anorthosite and represented in Plate VI., which, owing to a movement in the rock, have been drawn out in one direction. The irregular-shaped patches, differing greatly in size of grain, described as occurring in the massive rock, are also here represented by elongated streaks of similar character. This foliation is best seen where bisilicates and iron ore are comparatively abundant. When, as is sometimes the case, the rock is almost free from these constituents and all the plagioclase fragments have been , destroyed, it assumes a nearly uniform granular character, and no trace of foliation can be observed. The foliation, however, is usually distinctly seen, and in the arm-like extension runs parallel to the direction of the arm itself, that is to the strike of the gneiss, which it penetrates. Along the western border of the arm, the strike is exceedingly regular and remarkably well developed, as at New Glas- gow, but is especially well seen along the same contact further north ^ v tpd on range XI. of the township of Rawdon, on the road between the auorthosite. villages of Chertsey and Rawdon. Here the rock is seen to have a remarkably regular schistose structure, due to the alternation of thin layers of pure plagioclase with still thinner ones of pyroxene. The pyroxene bands might more properly be called leaves, as they are very thin, being frequently represented by mere parallel lines in transverse sections. When examined under the microscope, in thin sections or weathered surfaces, both they and the plagioclase layers are found to contain small cores or remnants of large individuals with trails of grains extending from them in either direction as before described. These give rise to the perfect foliation and the progress of the granulation is seen in a most astonishingly perfect manner, the cores being in the very act of breaking up (Plate VII.). These cores can occasionally be seen to be the remnants of very large individuals, which have sheared almost in the direction of the foliation, They are thus often long and narrow, some having been observed as much as twelve times as long as they are wide. \ m ^(■vcrftl »truotiin-4. MdVt'lllClltH MulwiHiiient to Holiecanie most complete, until finally the lost remnants of the larger individuals disappeared, and in the case of a pure anorthosite, a more or less evenly granular rock resulted. In the anorthosite, however, the remnants of larger individuals are seldom or never entirely absent, and in the great majority of cases the amount of interstitial material is quite small. Even when the granulation was most complete, the rock did not crumble into an incoherent powdei", but remained as hard and tough as ever, the grains, being unable to separate from one another on account of the great pressure to which TIIR MOUIN ANORTIIONITK. I in .1 cribecl next p structures anorthoHito, ;hh irrvK"''^!' nro ori^iniil 'heHO iin'gu- t the results j{uUir hiiiHls, etinite diren- e rock while ;«! by niove- ution nf the r front irrejj- i processes of ystiilliziitioM. renccs in the it, or to other The annuliir le rock which k'ould Heeni to were fiivour- [l been subso- inagnia which ystalline inas- pnt of a more iray described, Tom pressure en shown, the e crystalline rock grndu- attrition gave nts continued iHilly the last the case of a Ited. In the are seldom or s the amount e granulation lerent powder, eing unable to sure to which they were subjeoted, rolled over one another, remaining always within the sphere < >f cohesion. In this way, any ]H>rtions of the origini»lly niassivo rock diflTering in grain or composition from the rest, would be represented by bands, streaks or even lines in the resulting granulated anorthosite ; very coarse-grainml portions being represented by Imnds or streaks contain- ing large plagioclase remnants, tine-grained portions being represented by bandis or streaks where these are very small or even absent, while corresponding difTerences would np|)ear in the case of areas diflTering in mineralogical com]>osition. Tliese foliatetl or schistose anorthosites then, were prcKluced by move Siln»ti.s«- ment m a massive igneous rock, ami are not altered sediments, the '•"""•''«•»•'« , . ii"t iilttTi'd structure which they present Iteing, as has loeen shown, a cataclastic siclimtTitH, struct »i re. Ihat although this granulation and its accompanying phenomena are certainly the results of pressure to which the rock has been subjected, the effects of this pressurti are in certain resjiecls quite different from thiwe usually observed. As a general rule, in the ca.se of schistose structures prmluced by shearing, of which so many ••xcellent examples have lieen descril)ed by Lehmann and others, the breaking up of the constituents takes place principally along certain dctinite lines. Along these lines or bands, which are sometimes quite wide but which at other times sink to almost microscopic dimensions, the rock is r(;duced to a comminut«!d stlnce. 1. When the rock was still so far beneath the surface of the earth and so weighted down by the overlying rocks that breaking and shear- ing with the movement of the resulting masses was impossible. The ,^^' ''."'; '''♦"I'lv alterations in the character of the mass were probably induced very slowly, the constituents became granulated and the small broken parts moved one over another. The granulation progressed with the duration and intensity of this movement up to a certain point. Such a motion would present certain resemblances to that of a very tough pasty mass. 2. While the rock was still very hot and perhaps even near its melting point. This would explain why the pyroxene, which, accord- ing to the experiments of Foutjue and Michel-Levy, represents the stable form of the molecule at a high temperature, is not changed into amphibole, which represents the more stable form at a low temperature, wiiii,. v.iv as is usually the case in crushed and pulverized rocks. It is perhaps ''"'• owing to the same cause that no saussurite is formed ; still, the condi- tions necessary to the fonnation of these minerals are so little under- stood that opinions on this point cannot be ventured upon as yet. A clastic structure in many respects similar to that above described, in which plagioclase grains are twisted and broken or even suffer peripheral granulation, occurs in certain spc«cimens of the theralite of the Montreal Mountain, which also present a streaked appearance marked by variations in size of grain. Here it must also be regarded as evidence of motion, but of motion which in all probability Uy^k place before the complete solidification of the rock, being an instance of what Brogger has termed " protoclastic structure," for the field relations of this old volcanic plug show that it has not been submitted • to any great pressure since the mass solidified. This structure, how- ever, is only developed very locally in the rock, and in many sections no trace of it can be found ; nevertheless its occurrence here is of interest showing as it dous that the mere detection of such a structure VrutucluHtic here and there in an igneous rock is not indubitable proof that the *t™cturc. rock has been submitted to great pressure and has been crushed. It would thus seem that the clastic structure described as occur- ring in these anorthosites occupies, in a way, a position intermediate between the protoclastic structure of Brogger and the cataclastic structure commonly observed in sheared rocks. In the Morin area, then, we have a great intrusive mass of anortho- ReHume. site, or gabbro very rich in plagioclase, breaking through the Laur- 8A ^ il i|t Anortliosite jxinnesserj its presfiit characters in Cmiibi'inn times. Other aiiorthosite masses. IIG J QUEBEC. eiitiun, cuttinf; off successive horizons, including portions of the gneiss, sending an apophysis into it, and in Fome places bounded by a zone of rock which exhibits many characteristics of a contact product. This moss in most places shows irregularities in size of grain and in some places a streaked or irregularly banded structure, while in one part of the above-mentioned apophysis it is well foliated, which foliated structure there is reason to believe is a secondaiy one. It certainly does not represent a partially obliterated bedding as the earlier observers seem to have believed, while the c ^her supposed exidences of the existence of a great overlying sedimentary series, nf which it was supposed to form part, are also wanting ; the gneiss and limestone with which it was thought to be interstratified, really belonging to the Grenville serie,s, while the apparent interstratification of the anorthosite is due to intrusion. The whole is furthermore unconformably overlain by flat unaltered strata of Potsdam and Calciferous age, and thus possessed in Cambrian times the characters which it now presents, while the nature of the anorthosite and its relation to the Ltiurentian, lead us to suppose that it is much nearer in age to the latter than to the overlying Cambro-Silu- riar. probably not much more recent than the Grenville series itself. Other Anorthosite Masses. Strafigraphical Relationn and Petrography. In addition to the Morin anorthosite, there are in the district embraced by the present report twelve other occurrences of anorthosite lying to the south and east of the Morin area and much smaller in size. These are — commencing the enumeration from the west : — (1.) The Lakefield area — an area lying to the east of the village of Lakefield, situated partly in the Gore of the township of Chatham and partly in the parish of St. Columban. (2.) The St. J^r6me area, on which is situated the town of that name. (3.) Three elongated and approximately parallel aieas in the town- ship of Kildare and its Augmentation. (I.) Two rather larger areas on the east side of the township of Cathcart. (5.) Two occurrences, much smaller than the rest — one by the side of the River L'Assomption near the Pont des Dalles and to the east of MAM 1.1 OTHER ANORTHOSITE MASSES. 117 J he gneiss, a zone of ict. This 1 in some part of the structure |r does not •vers seem I existence pposed to which it Grenville site is due unaltered Cambrian are of the ippose tlmt tmbro-Silu- es itself. de district morthosite er in size. village of atham and vn of that the town- ownship of y the side the east of the village of Ste. Beatrix, the other a short distance to the west of the village of St. Jean de Matha. (6.) Three bands of anorthosite intercalated in the nearly horizontal gneisses of the township of Brandon. These anorthosite masses are from one hundred to several hundred yards in width, the greatest length of any one area being al)out seven miles. They run parallel to the strike of the gneiss, in which they are intercalated, and are usually well defined against, it, the most notal)Ie exception being the St. Jer6me occurrence. The gneiss, how- ever, sometimes appears to be more basic near the contact. The anorthosite varies somewhat in character in the different areas. It is usually coarsely crystalline, frequently showing a great variation in size of grain and resembling that of the Morin area, but it is per- haps on the whole richer in iron-magnesia constituents, and often con- tains minerals such as hornblende, biotite and in one case scapolite, which occur very sparingly, or are entirely wanting, in the Morin anorthosite. The anorthosite of these several areas also frequently contains garnet near its contact with the gneiss. It frequently exhibits in an eminent degree the granulated structure described in the Morin anorthosite, and has a more or less well marked arrange- ment of the constituent minerals parallel to the longer axis of the areas. ' As the several areas present certain diflferences, they will be con- sidered separately. The Lakefield Area. Thi.« is four and a half miles long and about a mile wide. The anor- -pj,^ LiiketieUl thosite of the peripheral portions is fine grained, foliaied, very poor in unorthositi?. bisilicates and weathers white. In the inner part of the area it is more massive and appears on the whole to be rather richer in iron- magnesia minerals, which vary in amount from place to place, often giving tu the rock an irregularly banded structure. It is crossed, as shown on the map, by two roads, while a third passes immediately to the north of it. In this area a rapid change in strike is observable, the anorthosite and its accompanying gneiss in the southern part striking, on an average, N. 45" W., while all about the northern extremity both rocks strike N. 20-50 E. 118 .T QUEBEC, A thin section from a specimen collected near the eastern side of the area, on the most southerly of the roads above mentioned, shows the rock at this point to be a typical anorthosite, the plagioclase pre- ponderating very largely, while the iron-magnesia constituents a\e represented chiefly by augite, in addition to which there are very small quantities of green hornblende and brown biotite. Less than a mile south of the southern edge of this area, at the very edge of the r^aurentian escarpment, a diabase dyke cuts through the gneiss which is here the country rock. The diabase, however, contains a great number of angular fragments of white anorthosite, which in many places are so abundant that they make up the greater part of the dyke. Under the microscope this anorthosite is seen to be a rather fine- grained variety composed almost exclusively of plagioclase, with a few grains of iron ore. The plagioclase, is however, largely altered into mica, the little mica scales being arranged principally in two directions parallel to the cleavage of the felspar (Section 415). These fragments, which wer- brought up by the molten diabase, probably mark an interground extension of the Lakefield area to the south. The St. J&ome Area, I'll' The St. JerAme anorthosite. Only a portion of this area, situated, as it is, immediately at the edge of the Laurentian region, is exposed to view. The southern part of it is covered up by the flat-lying Pali«ozoic strata, which come in a short distance to the south of the town. What proportion of the whole mass is represented by that portion exposed to view, it is impossible to say. It differs considerably from the other areas, not only in the fact that the anorthosite composing it is not so typical in character, but also in that there intervenes between it and the gneiss a zone of rocks of intermediate character. The anorthosite, or gabbro, as it should more properly be called, is best seen in the large exposures on either side of the Canadian Pacific railway track a few hundred yards south of the railway station at St. J^rdme. These are situated about the middle of the area as exposed, and towards its southern limit, and probably present the anorthosite in its most typical development, freest from contact effects, and nearest to the actual centre of the mass. Here the rock is fine-grained, usually foliated in structure, and weathers brownish-gray. In some places it possesses a more or less distinctly banded structure, due to the alternation of portions rather rich in bisilicates with others consisting almost entirely of plagioclase. Individuals of dark-coloured plagioclase, usually small in sixe, but n side of led, shows clase pre- uents ave very small an a mile ge of the eiss which IS a great 1 in many art of the ■ather fine- with a few ly altered lly in two 5). These 5, probably south. «ly at the ithern part 1 come in a ;ion of the view, it is : areas, not typical in 1 the gneiss 36 called, is dian Pacific r station at> the area as present the •om contact •ucture, and more or less tions rather t plagioclase. in size, but AOAMt. 1 OTHER AN0RTI108ITE MASSES. 119 J Dn»mJtrflitUi-UinjnfhyifL.S.S>chanl. PLAN Vicinity of SV Jerome Terrebonne County^, Que Scale Chains 80 )MUe rifiUKK 11. :£j. r: r II Legend Cambro-Silurian Potsdam Sandstone Laurentian ajjlaltitu limratcne TTTTTH Giuits MheJ ton* mJttutAnorthtite W V » V V w Anerthosite 120 J QUEBEC. i i Microscjipiciil dmrac'ter. Ciitaclastic Htrui'tinv. sometimes as much as six inches in length, are abundant in places. They are frequently seen to be curved or twisted, and are usually without good crystalline outlines. Under the microscope, the rock is seen to be composed essentially of plagioclase and pyroxene, the former preponderating largely, with hornblende, biotite, garnet, iron ore and pyrite as accessary constitu- ents, and with a few grains of quartz, calcite, chlorite and apatite. The pyroxene is light-green in colour, and is for the most part augite, which is often decomposed to calcite and chlorite. Some of it how- ever, is trichroic, in red, yellow and green tints, and is probably hypersthene. The hornblende, which is green in colour, and the biotite are present in but very small amounts. The garnpt is pink and perfectly isotropic; it is often well crystallized, and usually has some approximation to good crystalline form. It is generally associated with the iron ore, but often occurs in little strings through the rocks. The iron ore is black and opaque, and is often present in considerable amount. As in certain parts of the Morin anorthosite, there are probably two kinds of iron ore associated with one another, one rich in titanium and one poor in, or free from, that element. A portion of it is titanic iron ore, for leucoxene often appears as a decomposition product. The calcite is always present as a decom- position product, and the quartz, which is found in very small amount, is associated with the bisilicates, and may also be secondary. Little strings an inch or less in thickness, consisting of quartz and orthoclase felspar, and which run through the rock sometimes par- allel to the stratification and sometimes across it, are rather abundant in places, and are evidently distinct from the anorthosite and of later origin. The rock in its present form probably represents an advanced stage of granulation, for although but little is seen in the way of twisted grains and strain-shadows, these, as has been shown in describing the Morin anorthosite, are not distinct when the granulation is complete. The lar^e remnants of plagioclase, on the other hand, which occur abundantly in many places, in view of the light thrown on their origin by the study of the Morin anorthosite, point very strongly to an advanced stage of crushing. At the bridge over the North River at St. J^r6me, at the western edge of the area, as well as at a point about a mile and a quarter north of the above-mentioned exposures and near the northern end of the area, the same anorthosite is well exposed. At the latter place, how- ] UTHER AN0KTII081TG MASSES. 121 J fit in places. I are usually }di essentially largely, with lary constitu- and apatite, t part augite, e of it how- I is probably our, and the Eirnet is pink and usually i is generally rings through ben present in n anorthosite, I one another, 1 element. A appears as a as a decom- n very small be secondary. >f quart/, and tmetimes par- her abundant e and of later dvanced stage »y of twisted [escribing the I is complete, which occur n their origin rongly to an the western quarter north n end of the sr place, how- ever, an exceedingly well marked cataclastic structure is seen when the rock is examined under the microscope, the large individuals of plagioclase being twisted in a marked manner, broken apart, and embedded in a mass of granulated material rierived from them. This anorthosite mass is surrounded by a zone of rocks of varied character, many of which strongly resemble the anorthosite in appear- ance but which are quite diflferent in composition. They are well exposed back from the North lliver to the west of St. J^r6me, and by the side of the river to the north of the town. This zone includes a large amount of ordinary orthoelase gneiss, and in it occurs the band of crystalline limestone to the south-west of the * village, but it consists chieHy of rocks which in addition to augite and plagioclase contain variable amounts of hornblende, orthoelase and quartz, and which are thus intermediate in character between the gneiss and the anorthosite, some of the many varieties represented approachins; more nearly to gneiss and others more nearly to the anorthosite in character and composition. It is thus a matter of great difficulty to trace upon a map t\\'. exact limits of this zone. In the map (Fig. 11), however, this has been done as accurately as possible, ' with the aid of a microscopal examination of the rocks from a num- ber of {Ktints, which served to determine the actual character of such specimens. This zone surrounding the anorthosite probably represents a peculiar Border facias border facies of the latter, which, in many places, has been intruded " '""*'* """*'"■ into the gneiss parallel to its foliation, giving an appearance of inter- stratidcation, while movements induced by pressure subsequent to the intrusion, have served to render this appearance more pronounced. ^ Like the anorthosite, the rocks of this zone frequently present evidence of a more or less complete granulation, while the appearance of a certain amount of quartz in the anorthosite near its contact with tho gneiss, is a phenomenon observed in several cf the other anorthosite bands described below. About eight miles to the north-east of St. Jerome, jutting the Morin Xewdiasgow anorthosite close to its western contact at New Glasgow, and running 8"od''"- north for about six miles in a direction very nearly parallel to that of the limestone band in the gneiss just west of the contact, is a band of peculiar gabbro, nearly black in colour, which protrudes through the drift in a series of great roche moutonn^e bosses, contrasting in a marked manner with the white anorthosite through which it cuts. The band is narrow, and immediately to the north of New Glasgow !M 122 J QUEBEC. sends out an arm about a quarter of a mile long from its eastern side, which cuts aci-oss the foliation of the anorthosite. To the north this gabbro disappears on reacliing the Beauport River, being exposed be- tween the gneiss and anorthosite, and apparently cut off by a fault. It is seen again about a mile in a north-easterly direction from the point where it disappears, by the side of the road running from St. Calixte to St. Lin, and is then lost. Under the microscope the rock presents an extremely well marked cataclastic structure, the constit- uent minerals having been completely granulated under the great pressure to which they have been subjected. Areas in the Toicnship of Kildare and if 8 Augmentation. Kil'lare aiiorthoKitcs. These are is, three in number, are long and narrow, running with the strike of the gneiss, and might be referred to as bands. They are parallel to one another in position, and two westerly bands averaging a little over a quarter of a mile in width, while the most easterly is somewhat wider, being on an average rather over half a mile wide. They have lengths of six, five and seven miles respectively. Although in places covered with drift, they are generally well exposed, and being crossed by a number of roads are easily accessible. The three bands resemble one another closely in petrographical character. The rock is on the whole richer in bisilicates than the Morin anorthosite, approaching more nearly a normal gabbro or norite in composition. A specimen from the most westerly band, collected on lot 4 of rany a fault, n from the ig from St. ye the rock the constit- the great Hon. [inning with They are averaging a , easterly is a mile wide. Although d, and being three bands . The rock anorthosite, composition. jt 4 of range nined micro- igioclase and hypersthene, ell as a very ock shows a lach band it ,tion; usually, )n, parallel to B surrounding i by an indis- rock coincid- icter with the inctly foliated the marginal loling, but to seen. Quartz ] OTHBR ANORTH08ITK MASHES. 123 J also makes its appearance near the contact, and the rock having thus altered its character considerably, it is often difficult to determine its exact limits against the gneiss where the latter has been shattered and penetrated by the gabbro in a direction parallel to the strike. It is especially difficult to determine the exact position of the Baniu extremities of the several bands, these not only consisting of basic ' *'^* "l»>»«"t«- developments of the rock, but running into the gneiss for long dis- tances parallel to its foliation. Such basic rocks composed essentially of hypersthene, hornblende, plugioclase, and probably some orthoclase, and which may be a contact facies of the gabbro, occurring intimately associated with the ordinary orthoclase gneiss, are found as much as two miles to the south of the limit of the most westerlv of the three gabbro areas as represented on the map. In the most easterly of the three bauds also, no exposures are seen on the line between ranges VI. and VIII. of Kildare, the country being drift-covered, but to the south of the road there are large exposures of certain basic rocks in line with the strike of this area, which are supposed to belong to the gabbro, and the area has accordingly been represented on the map as extending southward as far as range VI. Areas in the Tottmahip of Cathcart. On the eastern side of this township are two areas of the anortho- Cathcart site separated by a narrow band of gneiss. They extend southward a short distance into the Seigniory of D'Aillebout, but how far they extend to the north-west beyond the ninth range of Cathcart has not been determined, the country in that direction, being covered with heavy forest and very difficult of access. Judging from the dimen- sions of the areas, as measured on the two roads which cross them transversely, as well as from the position of their southern limits and the shape of the other areas on the same strike further to the south, the northern limits assigned to them on the map are believed to be substantially correct. The rocks constituting these areas are well exposed on the two roads ■ above mentioned, which roads run approximately on the lines between ranges VI. and VII., and VIII. and IX., respectively, as well as on a road connecting these two and running through the western anortho- site area in the direction of 'its longer axis. The gneiss band separat- ing the two areas, as exposed on the more northerly of the two roads, consists of a finely foliated quartzose orthoclase-gneiss, with some bands of quart/ate, while on the southerly road it takes the form of a coarcie-grained basic gneis>, often resembling augen-gneiss in structure ,;; y 124 J QUKBKC. Viiriiiticm in Hize lit uriiiii. P(»llt tlfs DalleK nnortliosite. and frequently holding pyroxene and some plagioclase as well as inter- calated masses of the anurthosite. The anorthosite varies considerably in character from place to place, and is most typically developed in the western area. Here it is often very coarsely grained, almost massive, and shows the great variation in size of grain even in dififerent parts of the same exposure, described in the Morin area. In other parts of the area, it shows the indistinct banding, so common in anorthosites, and often a more or less pro- nounced foliation. The proportion of bisilicates varies considerably ; liypersthene and titanic iron ore are readily recognized on the weathered surface and in certain places many large broken individuals of plagioclase are also seen. The anorthosite thus strongly resembles that of the Morin area, though probably on the average richer in bisilicates and thus approach- ing more nearly in composition to an ordinary gabbro. It is, however, in the case of the easterly band more intermixed with the surrounding gneiss, the two rocks being in some phices apparantly interbanded, owing to the intrusion of the anorthosite into the shattered gneiss about the contact, and the development of a more or less distinctly foliated or banded structure in the whole by subsequent squeezing. Specimens of this rock which were examined microscopically, resem- bled very closely that of the anorthosite bands in the township of Brandon, described later on. Hypersthene is the chief iron-magnesia constituent, a few grains of augite and biotite being also present. Plagioclase is the most abundant constituent. The rock in a great majority of cases is in an advanced state of granulation, the whole process being exhibited in a striking manner by the thin sections. Area near Pont des Dalles on the River L' Asxoniption. This comparatively small occurrence is situated on the lliver L'A.s- somption at a point rather over one mile in a straight line east of the village of Ste. Beatrix. It is well exposed about a quarter of a mile west of the Pont des Dalles on a road which runs close to the river, but is'still better seen where the river cuts through the mass in a high cliflf on the south bank. The rock is coarsely crystalline and shows the u.sual variation in size of grain with here and there large masses of augite and hypersthene, and an indistinct parallel arrangement of the constituents in the direction of the prevailing strike of the surrounding ] OTilKR ANOKTIIOHITE MAHHKH. 1-25 ,1 Ifi i| is well as inter- n place to place, Here it is often great variation osure, described rs the indistinct )re or less pro- is considerably ; agnized on the )ken individuals ;he Morin area, i thus approach- It is, however, the surrounding tly interbanded, shattered gneiss r less distinctly nt squeezing. icopically, resem- the township of sf iron-magnesia ig also present. dvanced state of striking manner luption, the River L'As- ; line east of the uarter of a mile ose to the river, e mass in a high le and shows the large masses of angement of the the surrounding When examined on the face of the cliff above referred to, the rork ScuiNiIitf. often presents an approximately horizontal foliation, by apparently fol- lowing lines of motion. A specimen of this horizontal foliated variety which was collected and examined microscopically, wos found to present ti feature of interest in the presence of a large amount of scapolite, a mineral which has not been found in any of the other Canadian anor- tliosites. The iron-magnesiii constituents were found to be represented by augite and hypersthene in large amount, with a good deal of biotite and a little hornblende. The non-ferruginous constituents consist of plagioclase and scapi)lite, which are both present in abundance. Iron ore and pyrite, present in very small amount, complete the list of con- stituents. The scapolite is uniaxial and ne<>ative, polarizes in brilliant colours and presents the usual prismatic cleavages with parallel extinc- tion. The augite and plagioclase present the appearance of having been subjected to a process of granulation, but the grains do not show strain-shadows or twisted lamellic. This, as has been shown, is usually the case in the plagioclase of thoroughly granulated anorthosite. The biotite does not show such distinct evidence of granulation, while the scapolite occurs in large, clear, unbroken grains with uniform extinc- tion, which like the other constituents run in strings, sometimes in the plagioclase but usually between the plagioclase and the bisilicates. It is possible that the biotite may be a secondary mineral, and it is highly probable that the scapolite is an alteration product of the plagioclase, as in the case of the "spotted gabbro" of Norway and certain allied rocks in Canada and elsewhere * Anort/iositfi near' St. Jean de Mat/ia — Seigniory of De Ramsuy. About half a mile south-west of the village of 8t. Jean de IVIfitha, on .St. .r»'aii ile the road running toward the River L'Assomption, large exposures of .'mortiiositc. garnetiferous quartzose gneiss are succeeded by others of anorthosite. The latter rock is exposed for a width of about one hundred yards along the road and is succeeded by drift. It shows considerable variation in size of grain, weathers white, and is without foliation. When examined under the microscope, it is found to be a typical anorthosite composed almost entirely of plagioclase. The iron-magnesia constituent is augite. Biotite and apatite, both in very small quanti- * Michel Levy — 8ur une niche k Hphene, ainphibole et wernerite granulitique de Baiiile-Norvege. Bull. Sii. Tliifi' IniiuIk. 126 .1 IjUEBKO. ties, with a little titaniferoua iron ore and pyrite complete the list of constituents. The rock has undergone a certain amount of granulation. Anorlhimite Bands in t/ie Township 0/ Brandon. In the western half of thin township there are three important areas of anorthoaite, which occur interbanded with the nearly hori/xmtiil gneissen of this district. The most easterly of these, which is also tlio smallest, forms a hill on lot II, range IX., hy the side of the road which crosses near the front of the lot. It disappears beneath tlu' drift to the south of the road, and is not met with on the concession roads further south, nor is it again seen to the north, the townsliip along its strike in that direction being so heavily mantled with drift that very few exposures are met with. The associated gn«i8.ses strike N. 2!)' W. and dip at low angles to the east, the gneiss inmiediatoiy to the east of the anorthosite being a basic variety poor in quart/., while that to the west is rather fine in grain and highly quartzose. The anorthosite has the appearance of an interbanded or interstratitied mass, an appearance probably due to the rolling out of the whole com- plex under the great pressure to which it has been sul\jected. The rock is in some places massive, but elsewhere shows great irregularities ill size of grain, or is distinctly foliated, with strings of bisilicate.s arranged in a direction rudely parallel to the longer axis of the band and to the strike of the adjacent gneiss. On weathered surfaces large crystals of plagioclase, much cracked and broken, can occasionally he seen, but the rook usually presents the appearance of having Iteen sub jected to such prolonged movements that the large plagioclase indi- viduals have been entirely destroyed. Like'most of the small anorthosite Imnds described in this Report, these from the township of Brandon are usually richer in bisilicati's than a true anorthosite should be, and resemble in this respect certain varieties of anorthosite rich in bisilicates which occur in the eastern portion of the Morin area. The central of these three anorthosite bands in Brandon, seldom attaining and never exceeding a width of half a mile, runs through the township in a north-westerly direction, conforming to the strike of the gneiss, from lot 1 9 of range V. to lot 17 on the front of range XII., a distance of six and a half miles. It pinches out on range v., being bounded by almost continuous exposures of gneiss to the south, while on range XII., where but small exposures are seen, it disappears under the drift about Lake Mattabon. It closely re- sembles, both in stratigraphical relations and petrographical oharac- nplete the Vwi of >tof grunulatioii. ndon, itiiportniit (iFMis learly huri/untal which is also t\w Hide of the roiui tears beneath the m the concession rth, the townshiji lantU'd with drift sd gneisses stiikc leiss ininiediatflly ,y poor in quart/, highly (juartzosd. I or interstratificd of the whole com- I subjected. The reat irrej^ularities ings of bisilicates axis of the band ired surfaces large m occasionally be f having l)een sub plagioclase indi- ed in this Report, jher in bisilicates his respect certain !ur in the eastern ti Brandon, seldom mile, runs through •ming to the strike the front of range iches out on range I of gneiss to the asures are seen, it n. It closely re- rographical charac- r^i "iv; r; ! >'. Il I I I f )i ' i m i J ^ g 6 I- D ■J i o S3 <. > MS wo < r a: X I ^v , in 1 y'!r,\ I = !:• H s r. - as /', ^ X > s ^■^ WO V3 o X H a: o I 3 ] OTHRR AN0RTH08ITE MASSES. 127 J ter, the more easterly band above described, like it being apparently interbanded with the gneiss, the whole series as before dipping to the east at a low angle. At the contact near Liike Mattabon, elongated fragments of the anorthosite or gabbro were observed in the gneiss, having been apparently detached from the main mass by the move- ments which induced the foliation. The rock is coarse-grained, and as before the pmportion of bisilicates, chiefly hypersthene, is rather large, and the rock should be termed a norite rather than an anortho- site. Toward the middle of the band the tendency of the constituents to arrange themselves in strings or bands is very obscure, and the rock is almost massive. It is frequently very irregular in grain, displaying coarser or finer grained patches, the former often contain- ing masses of hypersthene, sometimes measuring from five to six inches across. The usual irregular-shaped remnants of large plagio- clasu individuals indicate that the rock has suffered an intense granu- lation. Toward the side of the band, a parallel arrangement of the hypersthene masses usually makes its appearance, coinciding in direc- tion with that of the adjacent gneiss. (Plate IX.) The most westerly of the three bands, is first seen alwut the middle Westerly of loi, 22 of range III., in the line of hills which forms the northern boundary of the drift plain occupying the southern corner of the township. It then runs in a north-westerly direction to the side-line of the township, which it meets on lot 22 of range V., where it attains a width of about a third of a mile, appearing in large expo- . sures, and is flanked on either side by gneiss. It was not observed, however, beyond the limits of the township, the country in the line of its strike in that direction being again drift-covered. In character and composition it is identical with the other two bands just referred to, under the microscope thin sections of the anorthosite composing the several bands resembling one another so closely that they cannot l)e distinguished apart. The iron-magnesia constituent is pyroxene, occurring in the foliated specimens as long strings of grains marking the foliation of the rock. It is for the most part a rhombic pyroxene (hypersthene), with strong trichroism in reddish, greenish and yellow- Mionwcopicul ish tints, but in most cases a certain amount of monoclinic pyroxene, intimately associated with the hypersthene and resembling it in appearance, but having an inclined extinction and no pleochroism, is also present. In every slide, a small amount of biotite and a few grains of iron ore are found. The felspathic constituent of the rock is essentially plagioclase, well twinned, and presenting the usual characteristics. An untwinned felspar is also present, usually in comparatively small amount, with rather strong dispersion of the 1 111 ,1- . I 128 J QUEBEC. No I'viilfiiCH (if catacliistic Kti'Hctim' ^I'liiinlatidii ill cc)iii|)U't<>. bisectrices, giving rise to pale bluish and brownish tints respectively on either side of the line of maximum extinction. This may be orthoclase. A few grains of pyrite and a few more or less rounded individuals of apatite are the only other constituents found in these rticks. The thin sections also aflPord indubitable evidence that these rocks have suflTered great internal movements. The large grains of felspar can be seen to have been twisted and fractured, and are often clearly seen to be in the very act of breaking up into .smaller grains. The same is true, though less noticeably so, in the case of the pyroxene, giving rise to a mosaic of grains of various sizes and shapes, which grains are 3een to have moved over and around one another, but in one plane, that, namely, of the foliation of the rock, which foliation in fact results from this movement. All the evidence goes to show that this granulation of the rock is a purely mechanical process. The pyroxenes are quite unaltered, and there is no evidence of any re-crystallization or alteration in the case of the felspar. The resultit g foliated rock differs from the original massive one only in being tine in grain and in the possession of a foliated structure, due to the granulation as above described Another fact before referred to in connection with the Morin anorthosite, and exemplified by all these granulated rocks — ordinary gneiss as well as anorthosites — is that in those portions of the sections where the granulation is complete, but little in ,'he way of conclusive evidence of any granulation could be obtained veni these to lie studied alone. In such cases mosaics of little angular grains are seen, each individual of which has an even or almost even extinction. Tliat this must be so, is realized when a large grain in process of breaking up is studied under the microscope ; for the strain to which such a grain is subjected, is seen to cause it to become resolved into a number of optical areas >)ounded by strain-shadows, but within such areas little or no strain is developed, so that when the next step is reached and the large grain actually breaks along the lines of maxiroum strain the result- ing grains, representing the areas in question, never show more than very faint strain-shadows while most of them, the strain being relieved, have a uniform extinction. A mosaic thus results, which while pro- duced by intense granulation bears, when studied apart from its sur- roundings, little or no evidence of its origin, and might be considered to have originated in other ways. It thus becomes evident that if the whole rock had reached the final stage of granulation, which stage would lie reached much sooner in the case of rocks fine in grain than 1 OTHER ANORTIIOSITE MASSES. 129 J respectively his may he [ess rounded ind in these that these je grains of ed, and are into smaller the case of IS sizes and around one jf the rock, the evidence r mechanical no evidence elspai". The one only in 3ture, due to I the Morin cs — ordinary ions of the 'he way of veM these to [• grains are I extinction. 9 of breaking such a grain a number of 1 areas little chedand the in the result- more than ing relieved, h while pro- rom its sur- considered it that if the which stage 1 grain than in those composed of large individuals, but little conclusive evidence as to its true origin might be obtained from a study of thin sections. The very thoroughness of the granulation would mask its existence, and it might be concluded that the rock had crystallized in its present form. This fact is an important one to bear in mind when studying rocks such as those at present under consideration. In this process of granulation, the pyroxenes while presenting all the phenomena above referred to, usually retain their form much better than the felspars. The examination of the sections shows, furthermore, that the move- Hock crys- nients in <{uestion must have taken place when the rock, if not com- J?,,^ .* n^ pleteiy crystalline, was almost so. All the minerals are granulated «)ccurretl. and must, therefore, have been crystallized out before the movement took place, and if any residual magma whatever was present when the movement took place, no sign of it <^an now be detected. Occasionally in a section a lit' ' ' ti faulting or shearing can be observed traversing the foliatioi 'rjelyand apparently developed at a later date. Along such lines tne granulation is exceedingly fine, differing in a marked manner from that of the rest of the rock and being in many cases iiccompanied by the development of calcite in large amount, thus showing that the conditions under which the original granulation took place were quite different from those under which the faulting originated. A table of analyses of aporthosites and of certain of their constituent minerals is subjoined : — 130 J Analyses of anortnosites. I O 'A < o \^ m < < o > 'A t « « > > QUBBKO. ^ 22 J5S? ? j I go I I «> I 'O'H© ig 2 ?8^^ in M 8" ^ - 5 9S g(N Jj I ^© I I « I •«©« IB 3 9 8 I Ig I I- S? g g SS S S i" ig l^?3 i I© s S8& 9i 30 C<3 2 a X S I S 'Isl*®® 8 3 I S I Jsl"*® 8 s5 ss; ,^s^ 9$ 35 Ig l©2© l«© I IS 8 8 s Is I -"Is®"® X X 5? ss , asg^ 2 Is* I la®^*. s is-^ I I^S*^ ' 8 X X X jf I j- I I 04 gib I I §5 *8 .v^TT*? X I ijrM I I 00©li5F-l© jg I^N I I J- I -r© i 8' g I ^« I I t-oib- g 1^© I I t-So©© 2 > X X ^ I J5© I I o©>o© I Wi 5^1 OINIM 2 2 X X X X i©t-M'* I 0000 I I 1-1 Q©e(s.^es©©« JH I 1 r- 8eq « n "OO, Oftdo. 'J CO po o 6. 50 SliSl s e I MO weioo s 9-4 trace 51 in 8 5 s^ , l^l-rol 1 1 goo© 1 ODSJ 1 acoo 8^ — I- 2 2 'S I- T^i 6cioO„do !/3 XIV. & XV. XVI. XVII. ft XVIII. XIX. XX. XXI. XXII. XXIII. XXIV. XXV. XXVI. XXVII. XXVIII. XXIX. XXX. XXXI. XXXII. XXXIII. XXXIV. XXXV. XXXVI. XXXVII. OTHER AKORTHOSITB HA88RS. 131 Large fragments of reddish plagioobwe from the anorthosite of NoteR to Chateau Richer. (T. S. Hunt, Geology of Canada, 1863). *»We. Fine-grained plagioclaae groundmaas, in which the former are imbedded. (Ibidem.) Hypenthene from the same rook. (Ibidem. ) Ilmenite from the same rook, with 4'9 p.c. of insoluble matter, quartz, etc. (Ibidem.) Bluish plagioolase in large fragments from another hand specimen of the ChAteau Richer anorthosite occurring imbedded in a fine granular groundmass of plagioclase. (Ibidem.) Similar plagioclase from an anorthosite boulder from the neigh- bouring parish of St. Joachim. (Ibidem. ) Very fine-grained, almost white anorthosite, from Rawdon (Morin area). (Ibidem.) Blue opalescent plagioolase from the Morin anorthosite. (Ibidem.) Bluish opalescent plagioclase from the summit of Mount Maroy in the Stete of New York, U.S.A. (A. R. Leeds, 13th Ann. Rep. New York State Museum of Natural History, 1876.) Very fine-grained yellowish anorthosite from the State of New York, U.S.A. (Ibidem.) Hypersthene from the anorthosite of Mount Marcy in the State of New York, U.S.A. (Ibidem.) Diallage from anorthosite. New York State, U.S.A. (Ibidem.) Labrador felspar, Paul's Island, Labrador. (G. Tschermak, in Rammelsberg's Mineralchemie). Labrador felspar, Paul's Island, Labrador. (Ibidem.) Plagioclase from a fine-grained, whitish anorthosite from Labrador (granular g^undmass). (H. Vogelsang, Archiv«iH Neerlandaises, T. IIL, 1868). Bluish-gray un twinned labradorite, Paul's Island, Labrador. (G. Hawes, Proc. Nat. Mus., Washington, 1881). I^brodor-rock. The chief rock of the vicinity of Nain, Labrador, (A. Wichmann, Z. d. D. G. G., 1884). Labradorite, Paul's Island. With traces of LijO and SrO ; v. 19 lost on ignition. (Jannasch, Neues Jahrb. fUr Min., i884, IL, 43). Labradorite, Paul's Island. The part soluble in HCl. With traces of LigO and SrO. (Ibidem, p. 43.) Labradorite, Paul's Island. The {lart insoluble in HCl. (Ibidem., p. 43.) Labradorite, Paul's Island. With traces of Li^O. (Ber. Deutsch. Chem. Ges., 1891, XXIV., 277.) Labradorite, Paul's Island, \yith tra^^8 of Li20. (Ibidem.) Notes on the Anorthositks occurring in other parts op Canada AND IN Foreign Countries. In addition to the anorthosites described in the present Report, a Anorthosites number of other similar occurrences, some of them of much greater ejsew^erfi m extent, occur in other parts of Canada. A noteworthy fact in con- nection with these anorthosites is that they are distributed along the H m Uil 1:; 1! ill Relation to Archiean Pro- taxis. AnorthofiitfH in Norway 132 J QUEBEC. southerly and easterly limits of the main Archaean protaxis bordering the great ocean basin in which the Cambrian rocks were deposited later on, showing that in these ancient times the eruptive rocks apparently followed the same law that now obtains in the distribution of volcanoes ; namely, that they occur along the borders of the con- tinents as belts around great oceanic depressions. By fur the largest of these is the great anorthosite area about the upper waters of the River Saguenay, which is known to occupy not less than 5800 square miles, and which may stretch across the headwaters of the River Betsiamites and connect with the area lying about the headwaters of the Moisie, in which case the area of the mass will be probably double that just given. Over this great area, the rock consists almost entirely of plagioclase. ' The other areas which lie chiefly along the north shore of the River and Gulf of St. Lawrence are described in my paper entitled " Ueber das Xorian oder Obsr Laurentian von Canada," and in other papers to which references are given in Appendix I. The largest developments of anorthosite with which we are acquainted outside of Canada, excepting those of Minnesota and the State of New York, described by Emmons, Kemp, Lawson and others, are probably found in Norway. The rock called by the Norwegian geologists Labrador rock, as well as some of Esmark's norites and many of the so-called gabbros of that country, are anorthosites. These rocks have been described by Kjerulf,* Reu8ch,f and othfrs. They form enormous mountain-masses, and are, as in Canada, some- times violet or brown in colour, and sometimes as white as marble. They are sometimes massive and sometimes banded or foliated. Many of them in hand specimens can not be distinguished from the corres- ponding varieties of Canadian anorthosite. They are intrusive rocks, and generally break through the gneiss. But in Laerdal and Vos-Kirchspeil, according to Kjerulf, they cut through beds of Primordial age, and are therefore probably somewhat more recent than the Canadian anorthosites. An accurate comparison of the rocks cannot yet be made since the Norwegian occurrences have not as yet been investigated in detail. But so far as we know at present, the rocks of the two countries are identical. •Kjerulf, Die Geologie des hUcW. und mittleren Norwegeii, p. 261. tKeuBch, Die fosHiIien fGhrenden krygtall. Schieft^r von Berj^en, p. H4. (is bordering ire deposited uptive rocks ) distribution 8 of the con- ir the largest iraters of the I 5800 square of the River leadwaters of >bably double most entirely 1 of the River itled " Ueber >her papers to Inch we are esota and the >n and others, ■ rock, as well d gabbros of f and others, 'anada, sonie- ite as marble, liated. Many )m the corres- ;h the gneiss, rulf, they cut bly somewhat te comparison ti occurrences as we know >.H4. NOTES ON FORRION ANORTilOSITES. 133 .1 In southern Russia, near Kamenoi-Brod, in the Governnient of Anorthosites Kiew, and in many other places in the governments of Volhynia Podolien and Cherson, large areas of anorthosite also occur. In these the labradorite predominates almost to the entire exclusion of other constituents. The rock occurs in some places in a coarsely granular form, which is dark violet or almost black in colour, and elsewhere as a porphyritic variety with large dark-coloured individuals of plagioclase in a light-gray groundmass. These varieties are said to pass into one another. Where the coarsely granular variety contains pyroxene, it shows ophitical structure like that observed in some parts of the Saguenay area. According to the description of ' these rocks by several authors,* they must resemble in a remarkable oanner the anorthosites described in this [)aper, and also exhibit the same varieties. They are found in the great district of granitic rocks which occupy this portion of the Russian Empire, which rocks, where they occur in the Government of Volhynia are classified by Ossowski as Laurentian. The uiagniticent pillars of labradorite in the Church of Our Saviour in Moscow, are from quarries in these rocks. Another occurrence of anorthosite of pai'ticular interest is found in Anortliimites Egypt. 'Sir William Dawson, while on a visit to that country in the "' "^tfyi'^- year 1883, observed a rock that resembles exactly the banded variety of the Morin anorthosite, and which had been used for a magnificent statue of Kephren, the builder of the second pyramid. This statue now stands in the Uizeh Museum, with a few other fragments of statues of the .same material. Through the kindness of the curator of the Museum, Sir William obtained a few small pieces of the rock for ex- amination. In the handspecimen the rock cannot be distinguished from the granular anorthosite which is found in the neighbourhood of New Glasgow in the florin area. It is fresh, t bright gray in colour and almost entirely composed of plagioclase, with a little hornblende, which mineral is occasionally intergrown with pyroxene. It is the foliated variety of the anorthosite, and the dark lines which are caused by the presence of hornblende can plainly be distinguished in the statue, especially on the right side. Sir William did not find the rock in place, but Newbold appears to have found it r.mong the very •Schrauf, Studien an der Mineralspeciea Labradorit. Sitzung8ber Wiener Aksd. 1860, p. !)90. — W. TarratK-nko, Ub«r den Labradorfeia von Kanienoi-Brod. Abhandl. d, Naturw. Ges. in Kiew. i886, p. 1-28. — M. K. De ('liroiistt! off, Notes pour servir A IVtude lithologiquc de la Volhynia. Bull. Soc. Min. Frtnce, IX., p. 251 (containing further references). t Dawson, Notes on Uneful and Ornamental Stones of Ancient Eg^'i)t. — Trans. Victoria Institute, Ix>ndon, 1801. I: i.\ 134 J QUXBBC. ancient rocks which form the mountainous country to the east of the Nile, where it appears to have the same geognostical relations us in Canada. It was probably prized by the Egyptian sculptors for the reason that it possesses a pleasing colour, similar to marble, while at the same time taking a better polish and being considerably harder. These anorthosites, therefore, are found in five of the countries where the Archnean has an extensive development : in Canada, in the United States, in Norway, in Russia and in Egypt. They are found in enormous masses in the first four countries, and their extent is not yet known in the last mentioned. To these occurrences others will probably be added us the Archaean of other parts of the world is care- fully studied. Post-ArcHjBan Dykes. Post-ArchiBftii Here and there throughout the area, but especially in its southern por- dykes. jJoq^ dykes of fine-grained black rock, allied to diabase in composition, occur cutting across both the gneisses and anorthosites. As these have not been observed traversing the Palreozic strata of the plains they are probably pre- Potsdam in age. In mode of occurrence they present the characters commonly seen in trap dykes. The walls are well defined and approximately parallel to one another, their attitude being nearly vertical. They frequently hold fragments of the country' *x)ck, caught up by the dyke-rock while yet in a molten condition, and can occasionally be observed to send otf lateral apophyses into the surrounding rock. The dykes can frequently be seen to be much finer in grain toward the margins of the dykes, indicating that the country-rock was comparatively cold at the time of their intrusion. There is no evidence whatever to show that these dykes have been subjected to the folding and deforming forces which have so profoundly affected the Archaean rocks of the region. They have been practically undisturbed since the time of their solidification. The prevailing course of the dykes is approximately east-and-west, but many of them run in directions almost at right angles to this. They differ greatly in width, ranging from five or six feet to over 300 feet — several over 100 feet wide having been observed — and are usually traversed by several sets of well marked joint plains. The rock is black on fresh fracture and usually weathers brownish. In the south-wes'b corner of the district, Sir William Logan noted the occurrence of black dykes in a number of localities, and considered le east of the alations as in ilptors for the rble, while at .bly hai-der. the countries /anada, in the ley are found extent is not B8 others will world is care- 3 southern por- n composition, As these have )lain8 they are ommonly seen nately parallel ley frequently jrke-rock while ^^ed to send off can frequently 1 of the dykes, d at the time low that these g forces which region. They r solidification. east-and-west, les to this. c feet to over rved — and are lains. hers brownish. n Logan noted and considered ] POST-ARCHiGAN DYKES. 135 J them to be portions of three large dykes running across the country in an approximately east-and-west direction, all of which were interrupted by the syenite intrusion mentioned on page 29 j. The most northerly of these dykes was traced by Sir William Logan Dykes noted as far east as lot 6 of range VI. of Chatham Gore, and what is in all ^y l«Kn«» probability its continuation was found on the line separating St. Colum- ban from the Augmentation of Mille Isles, near the north-west corner of the former. It crosses the road at this point, and has a width of 300 feet. On the same course further east, what is probably the same dyke is exposed at the foot of the falls on the North River, at the pulp mill, about three miles above St. Jt^rdme. It is exposed for a width of 105 feet, but only one wall is seen. The course of this wall is east-and- ^*' •Tf'oine. west. Further east still, a short distance north of Hte. Sophie, a whole series of parallel dykes, thirteen in number, and aggregating 69 feet in thickness, is seen within a distance of 200 yards. These also strike east-and-west. They possess a flow structure in some cases, and hold fragments of gneiss and quartzite as well as some of white anorthosite, indicating an extension of the arm of the Morin anorthosite under this locality, as might be expected. Although it is quite possible that these several occurrences do not represent one continuous crack or fissure, they evidently mark the same line of weakness, which may be represented by a series of shorter parallel fissures approximately in the same line, as is often seen in the case in such dykes. The line of wenknes8 has been now traced in a direction almost parallel to the edge of the protaxis, from the eastern side of the seigniory of Petite Nation, a distance of fifty-five miles, and in all probability continues still further to the west. The other dykes represented on the map in the district between^St. J^rdme and Ste. Sophie are much smaller in size. , One of the two more southerly dykes traced out by Sir William Logan, may find its eastward continuation in a dyke exposed at the immediate edge of the protaxis to the south of the Lakefield anorthosite and running N. 50° E. This dyke is filled with angular fragments of white anorthosite (although that rock does not occur in the immediate vicinity) which fragments must have been derived from an underground extension of the Lakefield anorthosite in this direction. Two other important dykes occur further north, cutting the Morin uykes cutting anorthosite. The first of these is exposed on lot 16 of range VII. aiiorthositw. of the township of Bawdon. It is seventy-five feet wide, and runs N. 47° W.', having been followed for a distance of a mile and a half. !tp: .ftl' I 8t. Lin dyke. II Diabase. 136 J QUEBEC. The other occurs on the third, fourth and fifth ranges of the township of Chilton, and runs parallel to the River Ouareau, near its eastern bank, for a distance of about two and a half miles, having a width of 120 feet. Another smaller dyke, ten feet wide and running N. 87° W., in exposed on the first range of the Augmentation of Kildare, near the line between lots 4 and 5 on the road. A numVjer of other smaller dykes which were olwserved do not here merit especial mention, with the exception of one which is quite different from those already referred to both in composition and mode of occurrence. This is found on the plains about one mile from St. Lin, being exposed in the bed of the Little River. The exposures, however, are not very good, so that the precise relations of the rock cannot be determined. It cuts the Chazy limestone apparently in the form of an intercalated sheet, converting it into a highly crystalline red marble, which has here been quarried. The river is paved with this trap for a distance of about fifty yards, a thickness of about ten feet of the trap appearing in a cascade which occurs at this point. The marble is referred to on page 153 .i, in the section treating of economic geology. The great dykes traced out by Sir William Ix)gan in the south-east corner of the area are referred to by him as dolerites,^ and would be classed as diabases in the modern petrographical system. The St. Columban dyke when examined microscopically (Section 361) is seen to possess a typical diabase or ophitic structure consisting essentially of plagioclase and augite, the former running in lath-shaped individuals through the latter. A small amount of green hornblende, which may be either primary or secondary, and a small quantity of iron ore are present as accessary constituents. The rock also contains another mineral which is not <;ommonly found in fresh diabases, namely, quartz, which occurs in considerable amount in micropegmatitic inter- growths with felspar, in the little corners between the other con- stituents. The supposed continuation of the dyke crossing the North River above St. J^rdme (Sections 273, 342) is almost identical in character and composition, the hornblende, however, being replaced by a small amount of biotite. The augite, which is of the common variety usually found in rocks of this class, often occurs in long narrow forms of irregular shape, and is twinned according to both the base and the orthopinacoid, and with it a lighter coloured malacolite is frequently associated in parallel intergrowths, as in the Konga diabase of Sweden •Geology of Canada, 1863, \>. 38. ] post-arciia:an dykes. 137 J the township ar its eastern ing a width of N. 87° W., is dare, near the ed do not here 'hich is quite tion and mode s from St. Lin, 3ures, however, •ock cannot be the form of an ne red marble, this trap for a eet of the trap The marble in tnomic geology. I the south-east * and would be Item. The St. on 361) is seen ing essentially ped individuals ide, which may of iron ore are ntains another bbases, namely, ;matitic inter- the other con- ising the Nortli st identical in ing replaced by ommon variety ; narrow forms le base and the is frequently )ase of Sweden Quartz in small amount, in clear grains or micropegmatite intergrowths, ' is present as before. The dyke (Section 338) occurring at the edge of the Laurentian protaxis to the south of the Lakeileld anorthosite, and which may represent an easterly continuation of another of Sir William Logan's dykes, is also a diabase of the same type, consisting of plagioclase, augite and iron ore, with a very little biotite, and the same micro- pegmatite intergrowth of quart/, and felspar in the corners between tho other constituents. It is, however, much decomposed. This quartz diabase with typical ophitic structure, occasionally hold- Quurt/.- ing malacolite, is apparently the normal rock of the great east and west dykes of the district. The quartz occurs in micropegmatitic intergrowths with the plagioclase and is in all probability primary, as it is found in the rock even where it is perfectly fresh. It belongs to the Kunga type of this rock described by Tornebohm in Sweden. Some of the smaller dykes in the district about Ste. Sophie and New Augite- (llasgow, which closely resemble these diabases in appearance, and i^""'"'*' probably have essentially the same chemical composition, possetis a minutely porphyritic character, phenocrysts of plagioclase and augite l)eing imbedded in a tine groundraass composed of the same minerals with iron ore and a little biotite. This groundmass probably cooled as glass, and has since taken on a crystalline character through a process of devitrification. They belong to the spilite type of the augite por- phyrites, and in one or two instances show an amygdaloidal structure. One of these dykes, twenty-five feet wide, was observed on the road about one mile north-west of Ste. Sophie, and another forty feet wide in the bed of the River Achigan on lot 16 of range IV. of Kilkenny. The two dykes above mentioned as cutting the Morin anorthosite, one on lot 16 of range V^II. of the township of Rawdon (Sections 626, 427), and the other on the third, fourth and fifth ranges of Chilton (Section 364), are identical with one another in all respects, and as they have almost the same course were probably intruded at the same time. Although having the same general composition, they are distinctly different in structure from both the quartz diabase and augite porphyrite above described. The rock is of medium grain, becoming fine-grained at the margins, and is black in colour but weathers brown. Under the microscope, the Rawdon rock is seen Dykt-iu to consist of large phenocrysts of well twinned plagioclase, having Jdiding' perfect crystalline forms and filled with minute dark dust-like inclu- microi)eg- .r. 11, .11 , • niatite. sions, giving it a dark colour, with large phenocrysts of pyroxene, also having a good crystalline form, embedded in a species of ground- m\ 138 J QUEBEC. H ( fraiio|ili.vi't> Htvui'ture, I mass composed of a most beautiful inicropegmatitic or granophyric intergrowth of quartz and plagioolase. This latter plagioclase is free from dust inclusions, the granophyric intergrowth being thus colour- less. A small amount of hornblende and biotite as well as a consid* erable amount of iron ore and apatite, the latter in large and well formed elongated hexagonal prisms, are also present in the rock. The plagioclase often occurs in beautiful Baveno twins, and a careful examination of the sections, combined with the evidence obtained from a crystallograpbic examination of the pulveri/ed rock after separation by heavy solutions, shows that two pyroxenes occur intimately inter- grown with one another, one a monoclinic aiigite of the ordinary type found in diabases, and the other a rhombic pyroxene having the parallel extinction, pleochroism and other optical properties character- istic of hypersthene. The granophyre constitutes a very considerable proportion of the whole rock, and makes the sections beautiful objects when examined between crossed nicols in polarized light. The intergrowth of the quartz and plagioclase is in some places very Kne but elsewhere rather coarse, and the polysynthetio twinning of the plagioclase in it can l)e plainly seen. The granophyre can often be seen to have started its growth outward from phenocrysts of dark plagioclase or of augite, as shown in Plate X. reproduced from a micro-photograph of a thin section of the dyke, showing the granophyre growing about a crystal of plagio- clase. The hexagonal crystal included in the plagioclase phenocryst is apatite, while the augite with good crystal form is seen on the right. It is doubtful whether any rock of this character hitherto described contains so large a proportion of granophyre. The rock is neither u diabase nor a gabbro, having neither the ophitic structure of the former nor the hypidiomorphic granular structure of the latter. The structure is rather a porphyritic one and exactly like that sometimes seen in the Konga occurrence before referred to. The constituents of the rock have separated out in the following order : — Apatite and iron ore, augite, plagioclase — the series concluding with the simultaneous crystallization of the quartz and plagioclase of the granophyre, which has all the characters of a primary structure. The rock contains 49*66 per cent of silica. This micro-pegmatitic or granophyric intergrowth of quartz and felspar will probably be found to be very widespread in its occurrence in the dykes cutting the Archaean in Canada, as it is known also in diabases of the township of Templeton, in the county of Ottawa, in granophync (ioclase is free thus colour- as a cotiflid' irge and well he roc-k. I, and a careful obtained from ter separation tiinately inter- ordinary type le having the ties chai'acter- )ortion of the 'hen examined growth of the iewhere rather ie in it can be lave started its tr of augite, as i a thin section ystal of plagio- e phenocryst is n on the right, lerto described )ck is neither a ructure of the fie latter. The that sometimes constituents of patite and iron e simultaneous nophyre, which rock contains of quartz and I its occurrence known also in T of Ottawa, in (jKol.iKIICAt. Ht'llVKY OK CAXAnA. Vol.. VIIl., Pakt J. I'LATK X.-(JKANOPHYRIC IXTER(}ROWTH OF t^UARTZ AND PLAGIOCLAHE ABOUT A PHKNOCRY8T OF PLAGIOCLASE- DYKE OX RANGE VII., LOT 1«, TOWNSHIP OF RAWDON. X 38. ] ECONOMIC OEOLOOT. 139 J the province of Quebec, while Dr. Lawson describes it as occurring abundantly in the dykes of the Bainy Lake district to the west of Lake Superior.* The dyke near St. Lin which, unlike the others, is found cutting Dyke near rocks of Cambro-Silurian age, is also eptirely different in composition. Its original character cannot be determined, as the rock is exceedingly decomposed, but it probably belongs to the class of nepheline or melilite dyke-rocks like those found associated with the nepheline syenites about Montreal and elsewhere. Hydrochloric acid dissolves about twenty-five per cent of the pulverized rock, which effervesces freely. Under the microscope (Section 389), nearly colourless a&gite, with rhombic pyroxene for the most part altered to a mixture of bastite and iron oxide, and biotite in large crystals bleached nearly white, can be recognized. Also in the groundmass is a colourless mineral, uniaxial and negative and readily attached by acids, which is probably nepheline. A mineral which is probably perowskite is also present, as well as a large quantity of light yellow garnet, often having good crystalline form, together with much calcite or other rhombohedral carbonates, the products of decomposition. While therefore the dykes occurring in the area are not very numer- ous, their study brings out a number of points of considerable interest. Economic Oeoloot. Minerals and rocks of considerable economic value occur at a num- ber of points in the area embraced by this report. The following occurrences are referred to, either on account of their actual economic importance, or because they have been supposed to be of value and have attracted, or are likely to attract, more or less attention. Those depositSL situated in the county of Argenteuil, to the south- west of the Morin anorthosite area, are not here referred to, as they have been examined by Dr. R. W. Ells, and will be described by him in a forthcoming report. Iron Ore near St. J^rdme, County of Terrebonne. Two and a half miles south-west of St. J^rdme, on the road which fy,-_ follows the northern bank of the North River, there is a deposit of st. J^rOme. magnetic iron ore. This occurs as several thin bands interstratified 'Report on the Geology of the Rainy Lake Region, Annual Report, Oeol. Surv. Can., Vol. III. (N.S.), p. 156 v. AnalysiH, 140 J QUEBEC. with a dark hornblende rock and with the red orthoclase-gneiss of this part of the area, the whole dipping toward the river at a very high angle. At the time of my visit, in 1886, the ore had been exposed by the removal of the drift at a number of points along its strike, and a small opening had been made at one place. Subsequently, from October, 1891, until March, 1892, it was worked by the Canada Iron Furnace Co., during which time about 365 tons of ore was taken out and shipped to the company's furnace at Radnor, and there smelted. The following information has been kindly supplied to me by Mr. Arthur Cole, B.A. Sc, who was engaged in carrying out the work : — " Most of the ore was taken out of a pit which, when abandoned, was about 35 feet deep, 10 feet broad and 12 feet long. The ore-bed varied from two and a half to three feet in width, and was for the most part free from gangue. At a depth of 35 feet the bed narrowed down to a few inches, and was then entirely lost. A drift was driven from the west end of the pit along the bed for about 40 feet, the floor of the drift being about 15 feet from the surface. " Work was then discontinued, but was resumed in August, lf<92, but this time at a point about 100 yards further west along the outcrop of the bed. The ore here was in beds varying from a foot to a foot and a half in width. These beds often widened, but then they would separate into two beds with an intervening bed of rock. " In some places the walls of the beds were very clearly defined, while in others the ore gradually faded away into the surrounding rock. About 50 tons was taken out of this opening, about ten feet deep and thirty feet long. " Work was finally discontinued early in September, as it was found that too much rock was being handled." A sample of the ore was analysed by me and was found to have the following composition ; — Per cent. Ferric oxide 5906!» Ferrous oxide 20"a07 Titanic acid none. Phosphoric acid 'OlS Sulphur 001 Insohible matter ,. . . 9'8W7 Metallic iron 02' 191 Phosphorus 007 Sulphur ... 001 BBi i-gneiss of this ,t a very high en exposed by s strike, and a quently, from i Canada Iron f/aa taken out there smelted, bo me by Mr. i the work : — 3n abandoned, The ore-bed id was for the I bed narrowed rift was driven It 40 feet, the August, lt<92, )ng the outcrop foot to a foot len they would ilearly defined, le surrounding ng, about ten IS it was found found to have Per cent. . . 5906!t 2f)-807 none. 016 001 .. 9m 02 101 007 001 ] ECONOMIC OE0LU6Y. 141 This analysis brings out in a striking manner the distinction be- tween the iron ores of the orthoclase-gneiss and those of the anortho- site, the former being usually free from titanium, while the latter is rich in this deleterious constituent. This ore, although so near the anorthosite, is quite free from titanium, while the similar ores in the neighbouring anorthosite areas contain a large percentage of this element. Most of the other iron ores of this area, with the exception of the bog ores, which belong to the superficial deposits, unfortunately occur in or associated with the Morin anorthosite mass, and are, therefore, highly titaniferous. To these belong the following deposits : — Township oj Rawdon — Range II., Lot 2. This deposit is near the village of Ste. Julienne, and although it has Rawdon never been worked has attracted a good deal of attention. It occurs in the Morin anorthosite, near the eastern edge of the arm-like exten- sion before referred to. The ore is found in a foliated white-weather- ing variety of the anorthosite rather rich in bisilicates, with a strike varying from N. 8° W. to N. 25° W. and a nearly vertical dip- Several black dykes, apparently of diabase, occu. ^n the vicinity. The ore varies a great deal in character, being much purer in some places than others, and often occurs in the form of bands, from a few inches to several feet in width, generally conformable, or nearly so, to the foliation of the anorthosite, but in a few cases cutting across it. Both the anorthosite and iron ore are much twisted and faulted, and it is difficult to det«rmine whether the ore has been erupted through the anorthosite or whether the cases where it cuts across the anortho- site are to be attributed to faulting. It, however, has a general trend in the direction of the strike of the anorthosite, the principal mass being exposed for about 200 feet at right angles to this direction. The " ore " appears to be in reality a variety of the anorthosite, and in most places too poor in iron to constitute an ore in the proper sense of the term. It is also highly titaniferous and contains iron-pyrites as a frequent constituent. A specimen collected by me and assayed by Dr. Hoffmann was found to contain : — Metallic ii-on 42'2!) |ier ct^nt. Titanic acid Larjce amount. II I* i ■ if !♦■ 142 J QUEBEC. Two samples examined by Dr. B. J. Harrington*, formerly Ohemist to the (Geological Survey, gave the following results : — I. 11. Metallic iron 38 '27 per cent. 40'71 per cent. Titonicacid 83-67 » 33 64 » while a third specimen, in which the iron was not determined, was found to contain : Titanic acid 36'09 per cent. ^ Township of Wexford — Range I., Lot 7. Wexford. On this lot a small opening has been made in a dark-coloured, heavy massive rock containing a certain amount of iron ore. The field relations indicate that this is merely a local variety of the Morin anorthosite, exceptionally rich in the darker coloured constituents of the rock, and a microscopic examination proves this to be the case. When thin sections are examined, the rock is seen to be composed essentially of a dark-coloured pyroxene, with plagioclase and iron ore. A not inconsiderable amount of apatite, with a few grains of pyrite, garnet and biotite, are also present. The proportion of iron ore is com- paratively small, this mineral being entirely absent from some thin sections. A specimen collected to represent the richest portion of the mass was examined by Dr. Hoffmann, with the following result : — Metallic iron 20'27 per cent. Insoluble residue 58".58 h Titanic acid Decided reaction. Not very far from this locality, a remarkable case of local magnetic variation was observed in surveying the road between Ste. Adele and St. Sauveur, where it runs on the side-line between the township of Abercrombie and the Augmentation of Mille Isles, on range X. of the former township, and thus near the margin of the Morin anorthosite. At one point on the road the needle suffers a deflection of 44° in a distance of 200 yards, returning again, further on, to its normal position. The road runs up a drifted valley and there are no rock exposures on it, the nearest e;(po8ures to the position of maximum deflection being 430 yards to the south-west and 70 yards to the north-east respectively, the rocks in both cases being the ordinary * Keport of Progress, Geol. Surv. Can., 1876-77, p. 476. ] ECONOMIC QEOLOGY. 143 J anorthosite of ,the district. Whether the variation ia caused by a body of iron ore, and if so the position of the latter, can only be deter mined by a magnetic survey of the locality. I Township of Chertaey — Range VIII., Lota 5 and 6. This deposit is also situated in the Morin anorthosite area, near its Chertaey. edge. It is, as in the case of the occurrence above mentioned, a variety of the anorthosite rich in iron. The anorthosite at this locality is rudely banded, some of the bands being poor in iron ore while others consist of a nearly pure ore. Large exposures which are very rich in ore occur all over the southern part of lot 6. The ore, although it has not been examined chemically, is in all probability, like the other iron ores occurring in the anorthosite, rich in titanic acid. Township of Chertaey — Range /., Lot 9. This deposit occurs in anorthosite which is associated with quartzose gneiss at the edge of the Morin area. Although containing a good deal of disseminated iron ore and locally considered to be of value, in no part of the deposit was the ore found to be sufficiently concentrated to be of economic importance. Township of Kilkenny — Range VII., Lot 7. This deposit is an impure ochre or limonite, occurring near the edge Kilkenny, of the Morin anorthosite and apparently derived from the alteration of iron-pyrites, which occur as an impregnation in a band of anorthosite intercolated in the gneiss near the limits of the main area. The band of rock through which this limonite is distributed has a considerable width, but could not be examined everywhere at the time of my visit, owing to the fact that the forest covering the hill was on fire. No mass of the iron ore over one foot in thickness could be found, and the deposit, I should judge, is valueless as a source of iron. A specimen of the limonite collected by me was examined by Dr. Hoffmann, and was found to contain : — Metallic iron .. .2675 per cent. In8oluble matter Large amount. It also contained a considerable amount of manganese, but no titanium. 144 J QUEBEC. Kildare. Boff ore in Joliette. Tmvnship of Kildare — Rnnye X., Lot 11. On this lot a deposit of bog iron ore was exposed in digging a drain. A trench three feet deep was cut through the iron ore without' reaching the bottom of the deposit, and it was exposed in the drain for a distance of about thirty feet. The deposit is probably of con- siderable size and the ore is similar in character to that so extensively worked and smelted further east in the district of Three Rivers. A large deposit of bog ore also occurs on the line of the Canadian Pacific Railway between Joliette and St. Gabriel de Brandon, in the County of Joliette. This has been examined by Mr. Giroux.* The Canadian Iron Furnace Co. has worked this deposit and expected to take out about 200 oar loads in 1891. This company has also worked a deposit on ranges III. and IV. of the township of Joliette. That on range III. is considered to be one of the best hitherto opened up by the company. It varies from twelve to eighteen inches in thickness and is about three chains wide by five long. All through the Joliette district, at intervals from the Laurentians to the St. Lawrence, deposits of bog ore have been discovered, and more or less has been taken out at a great many different points. The quality and richness of the ore is found to vary greatly from place to place. The Canada Iron Furnace ' Co. received from this district during the years 1893, 1894 and 1896 about 6000 tons of this ore. The occurrence of bog iron ore at other points in the drift of the south-eastern portion of the area is referred to in the Geology of Canada (1863), p. 685, as follows :— "Within four or five miles of the village of Industry (Joliette), there are several places in which bog iron ore is met with. One of these is partly in the township of Kildare, and partly in the Augmentation of the seigniories of Lanoraie and Dautraye, comprising a superficies of about nine square miles ; and it exhibits patches of ore in so many of the parts which have been cleared of forest, as to lead to the hope that it may become profitable. Among other localities in this region, the ore is found on the line between the first and second ranges of Kildare, •Summary Re|X)rt of the 0|)erationH of the tieoloffioal Survey for the year 1891, |). 43 A. Summary Re|X)rt of the ()|)eration8 of the (xeological Survey for the year 1892, p. 44 a. J ECONOMIC (iEOLOOY. 145 J ging a drain. ore without I iu the drain )ably of con- lo extensively Rivers. the Canadian indon, in the iroux.* The 1 expected to I. and IV. of (red to be one 98 from twelve I wide by five i Laurentians scovered, and I points. The from place to this district )f this ore. s s drift of the le Geology of try (Joliette), . One of these Augmentation I superficies of in so many of the hope that ■egion, the ore » of Kildare, For the year 1891, or the year 181t2, on the seventh and eighth lots; and on the. seventh lot, on the road between the fourth and fifth ranges. Other localities where the ore was observed were in Cflte Ste. Emelie and Cote Ste. Rose ; but these portions being still in part covered with wood, it is difficult to determine the extent of the ore, although it appears to be consider- able. Further to the east, this ore was also met with between the rivers Ste. Marie and Achigan and at the Seigniory of Lachennye." Ochre. — A deposit of iron ochre, of a dark-yellow colour, was observed on Oclire. the road between ranges II. and III. of the township of Kildare, about GOO yards northeast of the point where the road from the village of St. Ambroise de Kildare crosses this range-line. It occurs in the sandy drift which covers this district, and was exposed in an excavation about three feet deep. For a foot from the surface the ochre is impure, being mixed with a good deal of sand, but below this, as far as exposed, it was of a purer character. (,'ol(f.— At intervals during the past thirty years or more, locations ias of the deposit, were, when assayed, found to contain neither gold nor silver. Township of Chertsey — Range V., Lot 15. The country-rock is fine-grained anorthosite, in which there are a great number of bands and strings of a coarse-grained anorthosite, varying from an inch to two feet in width, and containing in many place.s disseminated iron pyrites. This latter constitutes the "ore.'' The location was worked for three years, about thirty years ago, and some eleven thousand dollars are stated to hiive been expended. The principal working consists of a shaft 35 feet deep. A certain amount of surface work was al'o done on the face of a nlid' of the anorthosite. The rock, having been raised, was carted a distance of about a mile to the bank of tho River Ouareau, where it was treated in a mill erected at that point. This, at the time of my visit, was fast going to decay. It contained a battery of five stamps as well as ten amalga- mating pans. Some gold is stated to have been obtained, although the <|uantity was insufficient to pay exjienses. A series of specimens were collected from the various parts of the exposure worked, with a view to representing an average of the "ore" which could with care be obtained. These were assayed by Dr. Hoffmann, and were found to contain neither gold nor silver. Township of Chertsey — Range V., Lot 7. On the southwestern portion of this lot there is a cliff of bluish gray quartzite with interstratified bands of white quartzite, both rocks containing in places a little pyrite. This rock has not been assayed, but is very lean in appearance. Township oj Chertsey — Range VII., Lot 0. Near the northern end of the lot the anorthosite is traversed by many veins of white and bluish (juartz, the largest seen being three feet in width. One of these veins has been opened up but there are no indications of the presence of gold to warrant further expenditure. \ Township of Kildare — Range IX., Lot 9. * On this lot a pit 25 feet deep was sunk about thirty years ago. The rock worked foi- gold consists of white and grayish quartz, t:ccur- ring as veins in the red and gray gneiss of the district, and conform- ECONOMIC GEOLOftY. 147 J awuti uf the 1 nor silver. there are a anorthosite, ing ill many i the "ore."' iars ago, and ended. The ■tain amount I anorthosite. of about a ited in a mill fast going to 5 ten amalga- led, although of specimens arked, with a uld with care ivere found to i;liflfof bluish te, both rocks been assayed, i traversed by 1 being three bu^ there are r expenditure. years ago. quartz, cccur- and conform- ing in a general way to the direction of their foliation. Thete some- times attain a width of two feet but present no indication of the pre- sence of any precious metal. Augmentation of Kildare — Range IV., Lot 5. The rock here consists of a more or less impure crystalline limestone Augmenta- associated with a gray quartzose gneiss. Both contain in places little Ki",iare. specks of pyrite or pyrrhotite. A good deal of work has been carried on at different times. This was commenced by Mr. Dupuis, of Joliette, who many years ago formed a company and put up a battery of five stamps, with amalgamators and other appliances. He worked the pyi-itiferous gneiss and states that he obtained gold from it but not in paying quantities. At the time of my visit in 1888, operations had been resumed and were being carried on by a small lo:'al company. The workings consisted of a shaft about 25 feet deep and two short tunnels, the second of these, in a band of crystalline limestone flanked on either side by gneiss. Three sets of specimens were collected for assay ; the first being some of the gneiss originally worked by Mr. Dupuis; the second from the roof near the entrance to the second tunnel above mentioned, from a spot from which samples assayed in Chicago were stated to have yielded $160 of gold to the ton ; the third from the east wall of the same tunnel at its end. These three sets of specimens wei e separately assayed by Dr. Ho£f- mann, and were found to contain neither gold nor silver. The rocks worked at this locality are not such as either from their character or mode of occurrence might be supposed to contain gold in paying quantities, and the result of the assays as given a bove shows the correctness of these negative indications. Township of Jiawdun — Range VII., Lot 27. A small excavation has here been made in rusty-weathering garneti- Rawdnn. ferous gneiss, which in some cases is micaceous and holds small strings of pyrite. The rock was stated to have been assayed and to have yielded gold in varying proportions. Specimens collected, however, were assayed by Dr. Hoffmann, and found to contain neither gold nor silver. lOj f 148 J QUEBEC. Township of Rawdon— Range VI., Lot 24. A similar rusty-weathering garnetiferous gneiss often holding a little graphite and some pyrite. The latter mineral is sometimes present in considerable amount. A series of specimens representing the average of a band of this rock about six feet in width were col- lected, but were found by Dr. Hoffmann, as before, to contain neither gold nor silver. Township oj Cathcart — Range V., Lot. 8. Cathcart. A gneiss, white on the fresh fracture, but for the most part so decomposed that excavations for foundations and other purposes several feet in depth have been chopped in it by means of an nxe. The decomposed rock looks like a hard ochre and contains in places disseminated graphite. It was found by Dr. Hoffmann to contain neither gold nor silver. " La Rarrif're " — Toirnnhip of CoiirceVea. Liv Barrierc. Near the south corner of the township of Courcelles, on the Mat- tawin road, a few hundred yards notth of the line between Tracy and Courcelles, there is another " gold mine " at a place called " La Bar- riere." A good deal of work has been done here by the "Compagnie des mines d'or de Mnttawin." A small quartz vein from six to eight inches wide and holding a little pyrrhotite was first worked, but sub- sequently a trench was excavated down the face of the gneiss cliff, in which the above-mentionetl vein occurred, but w ithout following any well defined vein. The gneiss is gray or sometimes white, often garnetiferous, and sometimes holds a little pyrrhotite and pyrite. It is stated that some specimens from this locality, assayed in the United States, have been returned as containing gold to t!o value of .S434 to the ton. Others holding less gold are stated to have contained several ounces of silver to the ton. Samples collected by Mr. Giroux at the mine, and others of the quartx assayed in the United States and returned as containing considerable quantities of both gold and silv**, were assayed by Dr. Hoffmann in the laboratory of the Survey au , were found to contain only a trace of gold and no silver.* Graphite. — (Iraphite. This mineral often occurs in considerable amount, in the rusty- weathering gneiss of certain parts of the area, especially in the eastern •.Summary Report of the 0|)erati(>iis of the Geological Survey for 1801, p. 4.3 A. ] ECONOMK: CEOLOdY. 149 .1 holding a sometimes ipresenting h were col- lin neither 3st pait so r purposes of an axe. ns in places tx> contain on the Mat- II Tracy and ed " La Bar- "Compaftnie ' six to eight ced, but sub- neiss cliif, in nllowinp any white, often pyrite. It the United of *434 to contained Mr. Giroux id States and d and silvx, Survey an . portion of the township of llawdon, N.N.E. of the village of llawdon, and on the continuation of the strike of these rocks to the north in the township of Cathcart, as well as still further north on the River Assomption. At none of the localities in this part of the area, how- ever, was the graphite found in sufficient abundance to make the deposit of economic importance, though tlu; geological conditions are such as to render the discovery of valuable deposits of graphite in this district highly probable. On the western side of the area, graphitic gneiss was observed on the Devil's River, in the western corner of the township of Archam- bault, whi!e extensive deposits of graphite are known in the extreme south-west portion of the area embraced by the accompanying map, in Grenville and the adjacent townships. These latter are referred to in previous reports of the Geological Survey (See Geology of Canada, 186;{, p. 794), but were not visited by mo since, as has been mentioned, the survey of this corner of the area was carried out by Dr. Ells. Further reference to them will be found in his report. Apatite. — Deposits of this mineral are also known to exist in the south-western A|>atit«-. corner of the area, and will l)e referred to in \Jr. EUs's report. The only occurrence of apatite known in the remaining portion of the area is that on range I., lot 33, of the township of Cartier. Here two openings, each about eight feet deep, have been made, on a coarse- grained granite vein six feet wide, cutting grayish garnetiferous gneiss. This vein consists essentially of quartz, white to dark-brown in colour, with white orthoclase, biotite and muscovite, the largest crystals of the latter being four inches in diameter. Apatite, tourmaline and garnet occur in smaller amount. One small crystal of pale-greon beryl was also observed. The apatite is found in small crystals, but not in sufli- cient abundance to enable the vein to be profitably worked, and the hopes entertained that the quantity of the mineral would increase on going down on the vein were not realized. The black tourmaline has all through the district been mistaken for coal, and the deposit is commonly referred to as a "coal mine." n the rusty- n the eastern Bin, p. 43 A. M ira. Lac Onareau. Mica in large sheets is found at a number of places in the parish of Mica. St. D mat about Lake Ouareau. At the time of my visit, in 1887, it had 160 J QUEBRC. IitfiiHuria] <>arth. t iarnet rock. not been found in place, but wua turned up in conHidemble quantities by the farmers when ploughing in certain tieldM. Spociniena obtained from one of these localities, where the road running down the west shore of Ijac Ouareau crosses the 11th range of the township of Chilton, when examined proved to be phlogopi e. Kildare, Hantje VJL, Lot lii. Phlogopite occurs on this lot, scattered through a pyroxene rock con- taining quartz, felspar, and a little tourmaline. Sheets six by eighf inches in si/e have been obtained. An opening has been made in the deposit and a small amount of mica shipped. Infusorial Earth, — A small deposit is mentioned by Mr. Uiroux as occurring nt'iir u small lake a few miles north of Chertsey, where the farmei-s use it for whitewashing their buildings. Garnft Rock, — Bands of highly garnetiferous gneiss are found at many localities within this urea, associated with rusty-weathering gneiss, (|uartzite, and crystalline limestone. At two localities these iii-e associated with bands of granular garnet rock, sufficiently thick to be of economic value. The first of these localities is on the rear of lot 20 of range VII. of the township of Rawdon, where several beds of a rock composed very largely of a red garnet, occur interst ratified with a fine-grained garnetiferous gneiss and white quartzite, the largest of the garnet beds being about two feet thick. Home portions of these beds consist of almost pure garnet, while in others this mineral is mixed with a little quartz, felspar and dark mica. A few blasts have been put in at this locality, but the deposit has not been worked as yet, although an abundance of garnet is to'be obtained, The microscopic characters of the rock are descrilied on page 84 .j. A still purer variety of the garnet rock in beds of considerable thickness occurs on the adjacent lot. No. 21 of range VII. of Rawdon, but these have not been opened up as yet. The other locality is one mentioned many years ago by Sir William Logan (Report of Progress, 1853-56, p. 43), and referred to by him as follows : — ** On the west side of the crystalline limestone at St. Jt'rAme, beds of garnet-rock are interstratified among the quartzite of the locality. ] RCUNOMtC OEOLOdY. IT)! ,1 le quantities ens obtained )wn the west township of ene rock con- six by eight , made in the urrmg ni'iir a armers use it niiny localities pis.1, (luartzitf, ssociated with B of economic of ranj,'e VII. ock composed a fine-grained ,he garnet beds beds consist of id with a little 1 put in at this t, although an c characters of y of the garnet Ijacent lot, No. n opened up as irs ago by Sir and referred to t. J«^rAme, Iwds of th(! locality. They vary in their composition, and Bometimos consist of a number of hyaointh-red garnets weathering pink, with yellowish-white prisms of diopside, among which are present small grains of greenish felspar weathering opac]ue white, a few minute scales of graphite and still fewer and more brilliant bhick grains supposed to be schorl. In some layers the garnets almost exclude tlie other minerals, but many varia- tions occur in the proportions in which they are disseminated, in parallel undulating bands, in the thi kness of the four or Kve feet composing the escarpment in which they are exposed, the hands being separated by thin divisions of quartzite and felspar. On the whole the garnets greatly prevail, and would appear to l>e in sufficient quan- tity for economic application." Crysta/Hnfl lAitifstone, — The heavy bands of crystalline limestone which occur in many parts Cr.vKtiilliiu' of the area and who.so distribution has already been referred to, have a '""•'"'*""'• very considerable economic value as well as a high scientific interest. Although too coarse in grain to afford a good (|uality of marble, and tiie local demand for building stone be:ng very limited, the limestone is * in many places burned for lime, the local re*|uirements being largely supplied in this way, especially in the remote districts in the rear of the area, which lie far from the Palieozoic limestones bordering the St. Lawrence. Near St. Sauveur, in the Augmentation of Mille Isles, the coarsely st. Sauviiir. crystalline bluish-white limestone, which here appears in very large exposures, has been burnt at intervals for many years, the suitability of the rock for the production of lime having been pointed out to the farmers in that 8ettlen\'>nt by Sir William Logan in the early years of the Canadian Survey. At Lake Ouareau, about the rear-line of the township of Chilton, as r . has been mentioned (p. 23 .i), a heavy band of similar limestone was Ouareau. discovered forming the greater part of two islands situated about half way up the lake and ne.ir its west shore, and also exposed elsewhere in the vicinity. The settlement here was, before this discovery, very remote from all known sources of lime, the necessary supplies of this material being drawn from St. J«^r6me, a distance of forty miles, over roads not always of the best. The inhabitants of the district will now build kilns and burn their own lime. To the west at St. Jovite, in gj .ferdine the township of De Salaberry, crystalline limestone is also burned, and in course of time the band which has l)een mentioned as passing down Trembling Lake will probably be similarly utilized. 152 J QUEBEC. Riiwdiin. Burned for linie. The limestones to the east of the Morin anorthosite area are also burned at a number of places. There are kilns on lot 28 of range X. of Kawdon, and also on lot 28 of range XI. of the same township, for which the very 3xtensi\o limestone deposits of that locality are utilized. The lime produced is said to be rather dark in colour, but clean and very strong, hardening into a sore of cement. On the northern continuation of the same band in the township of Cathcart, the lime- stone is burned at several points in the vicinity of St. Come. One of the principal kilns is situated on lot 23 of range IX., and has a capacity of 100 bushels. To burn this charge, about six cords of wood is required, which is to be obtained for fifty cents a cord ; firing being continued for three days and nights. The lime, which is pure, clean iind strong, sells for iyl.OO per barac (six bushels). Another kiln is situated on lot 27 of range XI. of the same township. The limestones at many other points above referred to in describing their distribution, would also afford abundant supplies of excellent lin. '. It may be mentioned, however, that the lime yielded by these Lauren tian limestones is not as a general rule so suitable for the finer plasters used in interior work as it is for mortar for brick and masonry, being usually darker in colour than that obtained from the Palteozoic limestones of the plains, and often somewhat " sandy," on account of impurities contained in the rock. Marble. — Maihlf. In addition to the limestones above mentioned, which have been burnt for lime, two occurrences of limestone have been worked as marble. The first of these is situated in the township of Cathcart, near the line between lots 8 and 9 of range VI., and was opened for marble in 1881 by Messrs. Guibauk and Dupuis of ooliette and Mr. William Burns of Rawdon. An excavation about 30 feet by 40 feet was made, and work was then suspended. Some specimens of marble of a good quality and taking a good polish are said to have been obtained. An examination of the location, however, shows that the marble, which is medium to rather coarse in grain, is mixed up with bands and strings of a groen sfrpentine and of a gray pyroxene rock, the latter seriously impairing its value as a marble. The '^(uantity also appears to be limited. The pyroxene, which occurs in the form of a granular aggregate somewhat resembling marble in appearance, is a malacolite having a specific gravity of 3-22^ .ad containing 52-48 per cent of 1 ECONOMIC OEOLOr.V. 153 J irea are also of range X. x)wnship, for locality are )ur, but clean the northern art, the lime- )UQe. One of as a capacity i of wood is firing being is pure, clean nother kiln is in describing i of excellent Ided by these e for the finer and masonry, the Palaeozoic on account of ch have been m worked as cart, near the for marble in Mr. William eet was made, 'ble of a good >btained. An irble, which is ds and string;) atter seriously appears to be )f a granular is a malacolite 8 per cent of silica, with a little alumina and traces of iron and manganese. The serpentine is derived from the alteration of this pyroxene, and can be seen to gradually pass into it in many places. 1 1 is sometimes light- green and sometimes deep-green in colour, and frequently runs through the pyroxene, dividing it up into rectangular areas separated by nar- row serpentine seams, giving the rock a somewhat striking appear- ance. A little brown mica, tourmaline and iron-pyrites are seen in some specimens. Another marble, quite different in character and age, occurs about a mile from St. Lin, on tiie road to New Glasgow. The rock belongs to the Chazy formation and ia exposed where a small stream tributary to L'Achigan River cuts through the drift and lays bare the under- lying rock. The marble is produced by the alteration of the Chazy limestone by an intercolated sheet of trap which occupies the bed of the stream. It is red in colour and forms a thin laj'er over the traps. , The marble has been quarried to a limited extent, but work had been suspended at the time of my visit. The trap, which has a somewhat unusual compof^ition, has already been referred to in describing the dykes of the area (p. 139 .i). Anorthoaitf. — ■ This rock, although it has Iwen but little used for building purposes, Anorthosite. might in many cases be employed with advantage for decorative con- struction. It may be obtained in unlimited amount in the Morin area, of any colour from deep violet to white. The opalescent varieties occur but sparingly in this district. To judge of its appearance when cut and polished, two large blocks, one of the violet and one of the white variety were collected, and six-inch cubes were prepared from them. Thsse were exhibited in the Colonial and Indian Exhibition held in London in 1886. The violet variety vr,s collected on the east- ern side of range II. of the township of Morin, and when polished presented a handsome appearance, but was rather dark in colour. The white variety, which was taken from the large exposures at New Glasgow, took a high polish, and in this state was found to bear a striking resemblance to marble. It is more difiicult to work than % marble, but would be more durable and would retain its polish better, especially in exposed situations, and might well be employed for many purposes in construction. On account of its toughness and duralnlity, this white anorthosite paving Ntone from New Glasgow has been extensively used for paving stones in the II 1 154 J QUEBEC. city of Montreal, especially on streets where there is a heavy traffic. A number of small quarries have been opened in the vicinity of New Glasgow, while a larger one is operated about two miles to the north of the village. The stone is blasted out in large blocks and is then dressed to the required size by means of large hammers. The industry which has thus sprung up is somewhat extensive ; up to the time of my last visit in August, 1881, 541,000 anorthosite paving blocks having been shipped to Montreal by rail. SUMMARY OF ARCH^AN GEOLOGY. 155 heavy traffic, le vicinity of ) miles to the blocks and is immers. The ve ; up to the hosite paving SUMMARY OF ARCH^AN GEOLOGY. 1. The Archiean rocks in this area are of Laurentian age, and are in part referable to the Grenville Series and in part to the Funda- mental Gneiss. 2. The Grenville Series contains gneisses, as well as limestones and quartzites, which are of aqueous origin, having the chemical com- position and the stratigraphical attitude of sedimentary rocks. With these are intimately associated, however, other gneisses which are of igneous origin. 3. The Fundamental Gneiss consists largely, if not exclusively, of igneous rocks in wi.ich a bandirg or foliation has been induced by movements caused oy pressure 4. Both series are penetrated by various igneous masses, of which the most important are great intrusions of anorthosite, a rock of the gabbro family, characteiized by a great preponderance of plagioclase. This rock is in places perfectly massive, but gener- ally exhibits the irregular structure which is so often observed in gabbros and which is brought about by a variation in the size of the grain or the relative proportion of the constituents from place to place. In additi^jn to this original structure, the rock almost always shows a peculiar protoclastic, cataclastic or granu- lated structure which is especially well seen in the foliated varie- ties. This differs from the structure characteristic of dynamic metamorphism in the great mountainous districts of the world, having been produced by movements in the rock-mass while this was still deeply buried in the crust of the earth and probably very hot — perhaps near the melting point. 5. The same granulated structure is also seen in all those gneisses which have been formed from massive igneous rocks by dynamic movements. 6. The fine-grained aqueous rocks of the Ijaurenliaii, on the other hand, have been alte ed chiefly by a process of recry»tallizaf -"u. 7. The "Upper Laurentian" or "Anorthosite Group" of Sir William liOgan does not exist as an independent geological series — the anorthosite, which was considered to be its principal constituent. 156 J QUEBEC. being an intrusive rock, and its remaining members belonging to the (xrenville Series. 8. In all casts of supposed unconformable suf)erpo8ition of the anor- thosite upon the Laurentian gneisses, which have been carefully investigated, the unconforraability is found to be due to intru- sion. 9. The anorthosites are probably of pre-Carabrian age, and .seen to have been intruded about the close of the Laurentian. 10. The Canadian anorthosites are identical in character with the anorthosites associated with the Archifan rocks of the Unitetl States, Norway, Rust-ia and Egypt. The Norwegian occurrences, however, are probably more recent in age than those of Canada. ANOKTHOSITES OF CANADA. 157 J- belonging to 1 of the anor- »een carefully due to intru- ), and seen to m. 3ter with the if the United II occurrences, le of Canada. APPENDIX I. Literature Rklatinc to thk Anorthosites of Canada. Adams, Frank D.: The Anorthosite Rocks of Canada. Proc. Brit. Ass. Adv. Sc, 1886. — On the Presence of Zones of Certain Silicates about the Olivine occurring in the Anortho.site Rocks from the River Saguenay. Am. Naturalist, Nov., 1885. — Preliminary Reports to Director of the Geological Survey of Canada on Anorthosite of Snguenay and Morin areas. Rep. of the Geol. Surv. of Canada, 1884, 1885, 1887. — Ueber das Norian oder Ober-Laurentian von Canada. Neues Jahrbuch fiir Alineralogie, «fec., Beilage Band VIII., 1893. Translated in Canadian Record of Science, Oct., 1894, Jan.,. 1895, July, 1895. Baddeley : Geology of a portion of the Labrador Coast. Trans. Lit. and Hist. Soc. of Quebec, 1829. — Geology of a portion of the Saguenay District. Ihidem, 1829. Bailey and Matthew : Geology of New Brunswick, Rep. of the Geo!. Surv. of Canada, 1870-71. Bayfield : Notes on the Geology of the North Coast of the St. Lawrence. Trans. Geol. Soc. London, Vol. V., 1833. Bell, Robert : Report on the Geology of Lake Huron. Rep. of the Geol. Surv. of Canada, 1876-77, p. 198. — Observations on the Geology, Mineralogy, Zoology and Botany of the Labrador Coast, Hudson Bay and Strait. Rep. ->.* the Geol. Surv. of Canada, 1882-84. Bigsby, John : A List of .Minerals an'. Organic Remains occurring in the Canadas. Am. Journ. Sci. (I), Vol. VIII., 1824. Cayley, Ed.: Up the River M' isi'j. Trans. Lit. and Hist. Soc. cf Quebec, Vol. V., 1862. Cohen, E.: Das Labradorit-fiihrendeGcstein der Kiiste von L>ibrador. Neues Jahrb. fiir Mineralogie, 1885, I., p. 183. Davies, W. H. A.: Notes on Esquimaux Ray and the surrounding Country. Trans. Lit. and Hist. Sr>c. of Quebec, Vol. IV., 1843. Emmons, Eb.: Report on the (ipology of the Second District of the State of New York. Albany, 1842. 158 .1 QUEBEC. Ferrier, W. F.: Notes on the Microscopic Character of some Rocks from the Counties of Quebec and Montmorency, collected by Mr. A. P. Low, 1889-91, Rep. of the Geol. Survey of Canada, 1890-91, L. Hall, James : Notes on the Geological Position of the Serpentine Limestone of Northern New York, etc. Am. Journ. Sci. (Ill), Vol. XIL, 1876. Hawes, G. W. : On the Determination of Feldspar in thin sections of Rocks. Proc. National Museum, Washington, 1881. Hind, H. Y.: Observations on Supposed Glacial Drift in the Labrador Peninsula, etc. Q. J. G. S. Jan. 1864. — Explorations in the Interior of the Labrador Peninsula. London, 1803. Hunt, T. Sterry : Examinations uf some Felspathic Rocks. London, Edinb. and Dublin Phil. Mag., May, 1855. — On Norite or Labradorite Rock. Am. Journ. Sci., 1870. — The Geology of Port Henry, New York. Canadian Naturalisti March, 1883. — Comparison of Canadian Anorthosites with Gabbros from Skye. Dublin Quart. Jouru., July, 1863. — Azoic Rocks. Part 1. Report of Geol. Survey of Pennsyl- vania. 1878. Jannasch, P.: Uber die Loslichkeit des Labradors von der Paulsinsel in Salzsaure. Neues Jahrb. fiir Min. 1884, II. 42. — Uber eine neue Methode zur Aufschilessung der Silicate. Ber Deutsch. Chem. Ges. Berlin, 1891, XXIV. 273. Jukes, J. B.: A General Report on the Geological Survey of New- foundland, 1839-40. London, 1843. Kemp, J. F.: Crystalline Limestones, Ophicaleites and associated Schists of the Eastern Adirondacks. Bull. Geol. Soc. Am., Vol. VL 1895. — Gabbros of the Western Shore of Lake Champlain. Bull. Geol. Soc. Am., Vol. V. 1894. — Illustrations of the Dynamic Mttamorphism of Anorthosites and related Rocks in the Adirondacks. Bull. Geol. Soc. Am., Vol. VIL p. 488, 1896. )f some Rocks ;y, collected by vey of Canada, bhe Serpentine mrn. Sci. (Ill), thin sections of 1881. In the Labrador .dor Peninsula, ocks. London, 3ci., 1870. iian Naturalist) ibros from Skye. *y of Pennsyl- der Paulsinsel 42. r Silicate. Ber lurvey of New- and associated jreol. Soc. Am., iin. Bull. Geol. of Anorthosites Geol. Soc. Am., AOAMI. ] ANORTHOSITES OF CANADA. 159 .1 Laflanime : Anorthosite at Chateau Richer. Report of the Director of the Geol. Surv. of Canada, 1885. — Report on Geological Observations in the Saguenay Region. Rep. of the Geol. Surv. of Canada, 1884. Lawson, A. C: The Anorthosytes of the Minnesota Coast of Lake Superior. Geol. and Nat. Hist. Surv. of Minnesota. Bull. No. 8, 1893. — The Norian Rocks of Canada. Science, May 26th, 1893. Leeds, Albert R. : Notes upon the Lithology of the Adirondacks. 13th Ann. Rep. of the New York State Museum of Nat. Hist., 1876; also American Chemist, March, 1877. Lieber, O. M. : Die amerikanische astronomische Expedition n'^ch Labrador im Juli, 1860. Peterm. Mitth., 1861. Logan, W. E., and Hunt, T. S. : Reports of the Geol. Surv. of Canada 1852-58,1863,1869. — On the Occurrence of O-ganic Remains in the Laurentian Rocks of Canada. Q.J.G.S., Nov., 1864. Low, A. P. : On the Mistassini Expedition. Rep. of the Geol. Surv. of Canada, 1885, D. — Notes on Anorthosite of St. Urbain, Rat River, ttc. Summary Rep. of the Geol. Surv. of Canada, 1890. — The Recent Exploration of the Labrador Peninsula. Cana- dian Record of Science, Vol. VI., No. o. — Report on the Geology and Economic Minerals of the Southern Part of Portiieuf, Quebec and Montmorency Counties, P.Q. Rep. of the Geol. Surv. of Canada, 1890-91, L. McConnell, R. G. : Notes on the Anorthosite of the Township of Brandon. Summary Hep. of the Geol. Surv. of Canada, 1879-80. Obiilski, J. : Notes on the Occurrence of Anorthosite on the River Saguenay. Report of the Commissioner of Crown Lands for the Province of Quebec, 1883. Packard, A. S. : The Labrador Coast. London, 1861. — Observations on the Glacial Phenomenon of Labrador and Maine, &c. Mem. Boston Soc. Nat. Hist., Vol. T., 1865. — Observations on the Drift Phenomenon of Labrador. Cana- dian Naturalist, New Series, Vol, II. 160 J gUEBEC. Puyjalon, H. de : Notes on Occurrence of Anortliosite on Gulf of St. Lawrence. Report of the Commissioner of Crown Lands, Province of Quebec, 1883-84. Ueichel, L. J. : Labrador, Bemerkungen iiber T and und Lf ute. Pe- term. Mitth., 1863. Hichardson, J.: The Geology of the vicinity of Lake St. John. Rep. of the Geol. Surv. of Canada, 1857. — The Geology of the Lower St. Lawrence. Rep. of the Geol. Surv. of Canada, 1866-69. Rosenbusch, H. : Mikronkojiisulie Physiographe der massigen Geateinc, 1880, p. 151. Hoth, J.: Allgemeine und ohemische Geolegie, Bd. II., p. 195. — Uber das Vorkummen von Labrador. Sitz. Bfirlin. Akad. XXVIIL. p. 697, 1883. Selwyn, A. R. C. : Report on the Quebec Group and the Older Crys- stalline Rocks of Canada. Rep. of the Geol. Surv. of Canada, 1877-78. — Summary reports of the Geol. Surv. of Canada, 1879-80. 1889. Selwyn, A. R. C, and Dawson, G. M. : Descriptive Sketch of the Dominion of Canada. Published by (ieol. Surv. of Canada, 1882. Smyth, C. H., Jr. : On Gabbros in the South-western Adirondack Region. Am. Journ. Sci., July, 1894. — Crystalline Limestones and Associated Rocks of North-western Adirondack Region. Bull. Geol. Soc. Am., Vol. VI. 1895. Steinhauer, M. : Note relative to the Geology of the Coast of Labra- dor. Trans. Geol. Soc. London, Vol. II. 1814. Van Hiae, C. R. : Correlation Papers, Archa-an and Algonkian. Bull. U. S. Geol. Survey, No. 86, 398. Vennor, H. G. : Notes on the Occurrence of Anortho.site. Summary Rep. of the Geol. Surv. of Canada, 1879-80 ; also Rep. of the Geol. Surv. of Canada, 1876-77, pp. 256-268. A'ogelsang, H. : Sur le La\)iadorite Color^ de la CfSte du Labrador. Archives N^erlandaises, T. III. 1868. Van Werveke, L. : Eigenthiimliche Zwillingsbildungen am Feldspath und Diallag. Neues Jahrh. fiir Min. 1883, II. p. 97. Wichmann, A. : Uber Gcsteine von Labrador. Zeits. d. d. Geol Ges. 1884. Wilkins, D. J. : Notes on the Geology of the Labrador Coast. Cana- dian Naturalist, 1878. n Gulf of St. *rown Lands, I Lt-ute. Pe- John. Rep. . of the Geol. igen Gesteine, ). 195. Jorlin. Akad. le Older Crys- v. of Canada, 579-80. 1889. Sketch of the V. of Canada, 1 Adirondack North-western VI. 1895. last of Labra- onkian. Hull. te. Summary Rep. of the 1 du Labrador. am Feldspath . 97. d. Geol Ges. Coast. Cana- TlIE SMELTING OF TlTANiFRROt'M IllON OUEH, 161 J APPENDIX II. The Smeltino ok Titanifrhoub Iron Ohes. As the anorthosites in different partH of the Laurenttun l'iei\iu'htly contain great bodies of iron ore wliich are invariably rich in titanium, the question of the possibility of smelting such ores is one of great practical importance in the Dominion. Several attempts to smelt these ores having proved unsuccessful the deposits in question have been looked upon as of but little value. Some recent investigations into the conditions under which titaniferous iron ores may be profitably smelted, by Mr. A. J. Rossi, have how- ever an important bearing on the subject, and IVIr. Rossi's paper pre- senting the results of his investigation, which appeared in " The Iron Age " for February 6th and 20th, 1 896, is accordingly here presented in a slightly abridged form. It is possible that some of the less highly titaniferous of these Canadian anortliosite iron ores might be worked if the piactice recommended by Mr. Rossi were followed. the smelting of titanifeuous iron ores. BY A. .T. ROSSI, new YORK. General Considerations. In a paper read at the Montreal meeting of the American Institute of Mining Engineers in February, 1893,* we have had occasion to treat a subject which has been the cause of much controversy — viz., the smelt- ing of titaniferous ores. In this paper, to which we will refer in what follows, we have placed ourselves as the champion of these much abused ores, and it was our good fortune in the discussion, short as it was, to see our efforts to rehabilitate these ores sustained by persons who occupy a prominent place in the metallurgical and scientific world. At that time we called attention to the fact that these ores had been smelted successfull}' in England in 1868, for a few years, at Norton-on-Tyne> by Dr. Forbes, quoting the able paper of Wm. M. Bowron.t then the chemist in charge of the works. In it ho explains in detail the metallurgical treatment, giving the composition of all the materials charged in the furnace (16 feet diameter at boshe.s and 50 feet liigh). -Vol. XXI., |). .832. tA.I.M.E., Vol. XI., p. 15!». I 162 J QURUEC. and that of the resulting slug. He says: "The uncertainty of the importation of the ores " — wliich came from Norway — " their lean- ness " (35 to 30 per cent of iron), " and the enormous quantity of titanic acid they contained " (38 to 40 per cent), " having militated serioii-ly against the commercial economy of the process after a few years' working ; ' but, as he adds, " the process, regarded as a piocess, was a perfect success." It was brought out in the discussion of our paper that: " Titan- iferous ores from Taberg ^Sweden) had been readily smelted for years ; " " that these ores are of special value, being usually entirely free from phosphorus ; " " that ores containing 5 to 6 per cent of titanium (8 33 to 10 per cent TiO^) have been regularly used for a long time in a largo establishment in Pennsylvania with very great advantage ; " " that there were furnaces using titaniferous ores, witli- out being aware of it, with beneficial results. '* These ores occur in large deposits in this countr}', " some of these deposits having been placed |iiovidentiaIly where they would prove the most inviting." Dr. Forbes iias stated emphatically that whenever the amount of titanium did not e.xceed about 8 per cent (13 to 14 per cent TiO.^) " no diffi- culty was found in working the ores cleanly and profitably." In the same discussion Dr. W. B. Phillips of Birmingham, Ala., summarized very clearly and teisely our own views on the subject when he said : " How long will American metallurgists cling to their opinion that these ores cannot be profitably treated?' "That the verdict recorded against them was unjust, based entirely on insuilicient grounds and far fro n creditable to the progressive spirit of American metallurgy ; " " that he, for one, believes that in the smelting of titaniferous ores there is abundant promise of success." As to the special qualities of the metal obtained from them, to whatever cause it might be attributed, the absence of phosphorus or some specific action, there seems to be a sort of amsfiisus otnninm, and the results of our own experiments on a large scale on the resistance, properties of chill, «kc., of mixtures in which entered the pig metal, afford another contribution to the truth of this assertion. " These ores yielded in England a forge iron which has brought double the market price of common iron. For use as a mixture to impart the properties of cold toughness to other irons, for making an iron to be mixed with other irons that are not quite up to the mark for boiler plates, sheets of cold stamping and the like, and for extra good iion generally these ores are most valuable, "f • A.I.M.E.— H. B. Not7.e, paper, Baltimore Meeting, Feb. !>. + W. M. Bowi'on, paper. 4MM. ] THE SMELTING OP TITANIFEBOUS IRON ORES. 163 J ertainty of tho y — " tlieir lean- us quantity of laving militated cess after a few liid as a process, that : " Titan- ily smelted for usually entirely 6 per cent of arly used for a with very great rous ores, witli- ise ores occur in ts having been i inviting." Dr. unt of titanium M).,) "no diffi- ably." ■mingliam, Ala., on the subject ts cling to their 1?' "That the f on insufficient 'it of American ^he smelting of from them, to f phosphorus or us omnium, and 1 the resistance, I the pig metal, (rtion. " These ight double the to impart tiie ig an iron to be nark for boiler extra good iron We have had occasion to mention the continuous smelting for years in this country, some 40 or 50 years ago, of similar ores that occur in large deposits in the Adirondacks.* We have given even the plans of a furnace of some 15 tons capacity which is standing there yet, and was erected after the successful running of two smaller stacks, fjack of railroad communications, the death of the principal interested parties and the civil war caused alone the abandonment of tlio enterprise, at the time, but in this ca'xygen ined only 1 -50 to 2 per 1 the amount of silica about 15 per cent of jribed to ores, fuel and by Dr. Forbes in Eng- »eing that in our case Aith an extra Hux of in his paper gives the ised in the furnace : — Old brickK. )!I0 SiO., r>!i(;o «0 Al.,0, -.'4 30 > 40 CaO L' 33 43 sent could not in this ting the titanic acid, a lace. It would corres- •4; A1,0..„ 1600, and ). The most extreme ed an oxygen ratio of E bases. The use of a 1 alone raise the SiO._, e titanic acid propor- stration of the possi- ] THK SMELTINIi OF TITANIFEIIOUS IRON OUES. 167 J bilities, as we would not certainly smelt such poor ores when an abundance of titaniferous ores can be found containing at least 55 per cent of iron and up to 64 per cent and more, with only 14 to 10 per cent or less of titanic acid. Such as it is, we have found the preceding compound perfectly fusible. It melted in a crucible, pla' ed in charcoal, through which we blew cold air at a pressure of li or 4 ounces. It was distinctly crystallized in bluish black needles. We may remark here in |)assing that sucii a small amount of silica could hardly be expected in a blast furnace. With ores containing 20 per cent of titanic acid and 50 to 53 per cent of iron, such as were smelted in our larger furnaces last summer, the slag still contained about 15 pei- cent of silica and only 35 per cent of titanic acid. With richer ores, of an average of 60 per cent of iron and 10 per cent of titanic acid, not less than IS per cent silica could be expected in the slag, with about 32 to 34 per cent of titanic acid. If the presence of silica were to be considered as an important element for the fusibility, these two latter slags ought to be still more fusible. Properties of Titanic Compounds. The results of the experiments which we have published in 1893, made either in crucibles or in our very small furnace, have been con- firmed by the subsecjuent ones and by the protracted test we have made this summer in a blast furnace of a practicul capacity. Titano-siiicates of lime, magnesia and alumina of an oxygen ratio of acid to basic element of 4 : 3, or still more acid, or slightly more basic, melt readily and prove more fluid at the temperature reached in a blast furnace working under unfavourable conditions as to heat. We will quote the following examples : — SiO., 11 il4 TiO, CaO MgO Ai.,03 moo Fi-O 11 il4 14 82 10-00 15-00 18-00 38-20 32 !t!) 28- '8 40 -."rt) 34 50 2;V40 2102 2()-00 24 00 27-00 (i-,50 !» 50 10 00 8 00 10.00 15 00 10 45 10-00 10 (10 12-70 5 00 4 DO (i i)0 2 00 4: 3 4; 2-3 4 : 2-5 4: 3 O.xyxcii ratio 4 : S'lO That the fusibility of a titanic compound does not necessarily depend upon the smaller amount of silica and the high percentage of titanic acid, but bears a more direct relation to the oxygen ratio, was proved by the following experiments : — 168 .1 QUEBEC. ilili:] Is It? ' '^ U-W ' til 1. By proper mixture of titanic acid (rutile) and bases we formed the following compound : SiO., 0-61 ; TiO.„ 44-05 ; CaO, 25-24 ; A1„0.„ 14-40; ATgO, 10-50, and FeO, 5-30, with an oxygen ratio of 4 : 4-78. It melted in the crucible. The fusibility, however, was decidedly affected ; the appearance was stony and lumpy. We repeated the experiment with practically the same results, the only difference being that there was increased Huidity and the fusibility was better when the temperature in the crucible could reach a good white heat. 2. We mixed together in a graphite crucible impure titanic acid, common rutile containing about 10 per cent of ferric oxide and 0-90 of silica, with lime, alumina and magnesia in such proportions as to form a decidedly acid titanate. Heated in charcoal, under a blast of 3 or 4 ounces of cold air, the mass (.500 grams) melted completely. The compound was beautifulh' crystallized throughout in fine bluish black needles. We repeated this experiment several times, and have obtained several pounds of this curious substance, of which we have given specimens to the School of Mines of Paris and New York (Columbia College). Its composition, on an average, was : SiO„, 0-72; TiO,, G5-.53 ; ALO,, 10-92; CaO, 14-60; MgO, 7-30, and FeO, 090. What is characteristic and of great importance is that practic- ally all the iron of the oxide of iron of the rutile separated cleanly at the bottom in the shape of a metallic button, a very small j^ercentage of the iron only finding its way into the slag. The button was decidedly gray iron, No. 3, if not higher yet, in grade. There were no signs of the formation of cyano-nitride of titanium where the button touched at the bottom the graphite of the crucible. The oxygen ratio in this ease was prac.ically 4 : 2 (exactly 4 : 1-86). In another experiment we tried to reproduce the mineral orthoclase, on a titanic base, by mixing together proper projjortions of rutile, freed from iron as much as possible, and alumina and potash. Oriho- ciase has a composition of SiO., 64-6 ; Al.^O..,, 18-5; K.^O, lt>-9. It melts at 6 (Dana) and has been found occasionally in crystals in some furnace scoria' in Germany. Its oxygen ratio is 4 : 1-33(3: 1). By replacing the 64-6 of silica by such an amount of titanic acid as would contain as much oxygen (864 TiO.^) we have obtained a compound of the following composition: TiO.,, ()7 to 70; AI.^O.,, 14-30, and K.,0, 1700. It melted and crystallized, but not us perfectly as the preceding compound. Its fusibility was certainly less. Magnesia, alumina and lime appear to form with titanic acid compounds more fusible than others containing, with alumina, even such a percentage of potash as 17 per cent. ADAM*. ] TIIK HMKLTlNCi OK TITANIKKROUS IHOX (»KEH. 109 and bases we formed 4406 ; CaO, 25-24 ; h an oxygen ratio of sibility, however, was A lumpy. We repeated Its, the only difference ? fusibility was better h a good white heat. I impure titanic acid, ferric oxide and 0-90 iuch proportions as to ircoal, under a blast of lelted completely. The ut in fine bluish black ral times, and hiuc ce, of which we have Paris and New York avertige, was: SiO„, ; MgO, 7aO, and FeO, jrtance is that practic le separated cleanly at very small j ercentagc ag. The button was grade. There were no ium where the button )le. Tiie oxygen ratio 56). the mineral orthoclase, projtortions of r utile, I and potiish. Or' ho 18"); KJ.), It)'.). It ly in crystals in some s 4: 1-3.3(3: 1). By titanic acid as would obtained a compound 0; Al,0..,, 14-30, and ot lis perfectly as the linly less. Magnesia, icid compounds more len such a percentage Briefly, the presence of titanic acid, even in large excess and with- out silica, in a substance, is far from being a cause of infusibility a priori if it is judiciously combined with the proper bases in suitable proportions, Within the limit which we have biiefly indicated there are, of course, many intermediary mixtures which, according to circumstances and the materi.ils available, could form the basis of very ftisible and fluid slags. In our blast furnace experiments of last summer the temperature of the blast was not civer 400 degrees F., and its pressure not more than 1 to 1| pounds, and still we had no trouble whatever to run from oi'dinary ores non-titaniferous slags of a ratio of oxygen of silica to oxygen of bases of 4 : G (2 : 3) — that is, of such a type as corresponds to the h<»ttest working with blast at 1400 degrees F. under a pressure of 8 to 10 pounds, and to the darkest grades of iron most charged with silicon ami graphitic carbon. The iron was white, and contained but a few tenths of 1 per cent of silicon. Though high enough to melt the more refractory silicates admissible in a blast furnace, the temper- ature was not sutticient to reduce the silica. This has a direct bearing on the smelting of titaniferous ores as corroborating the observations of Dr. Forbes in his practice and showing that such conditions can be made to prevail in a furnace as will melt the most refractory slags admissible and reduce the oxides of iron, and still they will not be such as lo reduce the silica, and still less the titanic acid. Under these circumstances the furnace cannot be troubled with "titanium deposits," as it has been claimed. These deposits consist of cyano-nitride of titanium, which supposes for its formation not only the i eduction in the furnace of titanic acid to titanium, but the highest temperatures and other conditions. We have experimented considerably on this particular point, and inasmuch as under certain conditions, of which we may have to speak at some future time, and which were intended to secure the formation of this cyano-nitride which we wanted to produce, we failed to obtain it, we have reasons which justify us in taking exception to the too sweep- ing assertion in regard to the formation of these deposits. Some of the slags run in our furnace last summer contained as much as 32 to 35 per cent of Til )^ and IG to 14 per cent of silica, with alumina, lime and magnesia as bases ; their oxygen ratio was 4 : 3. We made a number of analyses of such slags and in all cases we found them to dissolve completely, without any residue, in hydrochloric acid in the cold if very finely pulverized or under a gentle heat. The silica and 170 J QUKBGC. : V'\ titanic acid separated in a jjeiatinous state as the substance was heated. Had the titanic acid heen merely carried mechanically, even partially, by the slag as so much infusible sand, it would have separ- ated as an insoluble residue. This was never observed, and certainly furnishes the best proof that we had to deal with a detiiiite compound, a titanosilicate. It explains why compounds containing a larj,'e amount of a substance infusible jjer ki; tlie titanic acid, may prove quite fusible when this titanic acid can be cairied into a deKnite com- bination with the proper bases, and also explains the tendency of these compounds to crystallize. It may be arjjued that ei'-cumstances may so occur in the running of a blast furnace smelting any kind of non-titaniferous ores that they would lead to an obstruction whose removal would recjuire forcing the heat and the pressure of the blast, anfl that these circumstances in the special case of titaniferous ores wouKl be favourable to the formation of titanium deposits by the reduction of tlie titanic acid. The ten- dency of our days is to have in charge of the furnace competent per- sons capable of judiciously proportioning their charges from analyses made from day to day of the materials used, and such accidents have become certainly much more rare. , At all events this objection has been anticipated by Dr. Forbes, and, in the paper of Mr. Bowron referred to, a ready mode of relief is indicated. He says : " Throw oft' the titanic ore, and using non- titaniferous ore for a while, raise the heat and pressure of the blast and run the furnace on easily fusible slags until obstruction is removed ; then resume the use of titaniferous ores." The charges of the furnace were as follows : Coke, 2240 lbs. : ore, 2240 lbs.; calcite, 1200 lbs.; old bricks, 500. Making the proper calculations, he finds that from ores, coke aiid fluxes there could be expected a total amount of cinder-making materials of 2;J47'()6 lbs. for every ton d ore used in the charges, 2"75 tons of ore being required per ton of pig metal with an ore carrying 36 per cent of iron. As- suming for convenience sake, and which is practically sufficient, that all the iron goes into the pig metal, this gives per ton of pig 6456 lbs. of slag, and a consumption of 4675 lbs. of fluxes. The resulting slag, as run from the furnace, had a composition from analysis by Mr. Bowron of: SiO,,, 27-83; TiO„ 3618; CaO, 24-36; Al.O.,, 9-18 ; MgO, 0-60. As will be seen, the amount of silica present, 27-83, is still high enough to form with the 9-18 alumina and 24-36 of lime (independently of any titanic acid as an acid element) a perfectly fusible slag. It would correspond, reduced to a percentage and omit. the substance was il mechanically, even it would have separ- served, and certainly a definite compound, cimtaining a large inic acid, may prove 1 into a definite com- lins the tendency of occur in the running iferous ores that they Id retjuire forcing the 3 circumstances in the * lable to the formation tanic acid. The ten- rnace competent per- •haiges from analyses 1 such accidents have ipated by Dr. Forbes, •eady mode of relief is ore, and using non- pressure of the blast until obstruction is es." Coke, 2240 lbs. ; ore, Making the proper fluxes there could be ials of 2;J47-()6 lb.s. for of ore being required oer cent of iron. As- itically sufficient, that per ton of pig 6456 (luxes. The resulting tion from analysis by CaO, 24-36; Al,0,, unt of silica present, alumina and 24"36 of id element) a perfectly percentage and omit. •] THE 8MELTINO OK TITANIFEUOUH IKON ()KE8. 171 ,1 ting the titanic acid, to a composition of: SiO.j, 44'88 ; CaO, 39'29 ; Al.jO,,, 14-80; MgO, 100, with an oxygen ratio of 4:310, nearly. This is a very fusible blast furnace slag, not very basic, not even corresponding to the darkest grades of iron. Let us apply exactly the same mode of calculation in our tase, assuming the same ore and fuel and the same (|uantitie.s of each in the charges, but using a magnesian limestone not any more siliceous than Forbes's calcite, for fairness of compariscm. The dolomite chosen has a composition similar to that of the ore we have used this summer in our larger furnace (except for amount of silica). It contained SiO..., 0-90 ; CaO, 3900; MgO, 1200, and Al.XJ..,, 2 to 3. It is easy to calculate that for every ton of ore and fuel in the charg'S 1000 lbs. of such dolomite stone would be sufficient to obtain a slag of the composition SiO.^, 10-78; TiO., 4908; Al.O.,, 8-10; CaO, 2180, and MgO, 1021. The total amount of slag from the materials of the charges per ton of ore would be found to be 1788-78 lbs. Per ton of pig metal we would have 491934 lbs. slag, as against 64.'J6 lbs. as before, a saving of 23-80 per cent on the amount of cinder to melt, and consequent saving of fuel, and 2750 lbs. of magnesian stone, as against 4675 lbs. of fluxes, calcite and bricks, a saving of 41-30 per cent on the amount of fluxes added, although we have assumed the same (juantity of coke to be recjuired in both cases. Of course it is not in our province, within the limits of thi;. article, to discuss all that could be done in such cases. It wouk' >>-ti'.inly depend on the circumstances which would have been likely ^ cause the obstruction, and others which could be only judged on the spot, and which might occur with any kind of ores. The cause may be the use of an excess of limestone. It is a recorded fact that furnaces smelting non-titaniferous ores have been thus choked up by such an exce.ss of lime in the slag, so that it was too pasty to tap, and infusible blocks weighing thirty tons were formed, the removal of which required blasting. But the throwing off of the titaniferous ores for a while and the use of ordinary ores in their stead would at once create the ordinary conditions of practice. Furthermore, in the special case considered we could suggest several means which could prove efficacious. , Blast Fiirnare Tests. When we had to make a practical test of these titaniferous ores last summer, conditions of economy imposed upon us the necessity of adopt- ing a smaller scale than we would have desired. We decided on build- 17l' .1 (/I'KHEC. ing a furnace of about three toiiN daily capacity, u size sufficiently large already to judge practically of the advantages of a certain treatment and to furnish valuable information, convinced that, if we were suc- cessful in these conditions as to running of slags, reduction of the ores, «kc., we would be certain to obtain much more satisfactory and especially more economical results in a larger furnace provided with modern improvements. For tlie same reasons we did not judge it necessary to complicate the construction by using a cup and cone, and for simplicity and economy sake we built our furnace open top. We could not in such circum- stances expect to obtain a very high temperature of blast ; in short, we placed ourselves in conditions of running rather unfavourable. But as it was important also to determine as much as possible the relative economy, if any, of the melting of titaniferous and iion-titaiuferous ores, we decided to run the furnace for a certain time Hrst on ordinary ores, such as Lake Superior Iwematites, in order to study its working And ascertain what we could expect from it as to production, quality of pig- metal and amount of fuel required per ton of pig-metal before we should begin to use the titaniferous ores, liy so doing we secured, we believe, n reasonable basis for a useful comparison of the economy of smelting tlie two classes of ores, or of the different treatment of the same ores, whatever might be the size of the furnace, since in both cases we were placing ourselves in exactly the same conditions as to apparatus used, temperature, pressure and volume of blast. We give below the composition of the materials which entered the furnace from actual analyses made by the chemist in charge, sup- plementing them by such others as we have had made by different analysts in New York, or which have been furnished to us by outside parties. SiO, . , Al,<), Ca( ) . . M^O S P.. . Fe . Kon-titanife.roHn Ores. — Lake Siipei'ior Ha-matites. Clii'liiist ill c'liarK* 4 -.58 5 24 9 l(i 7 1'.» (••2!» 42 1:H2 03 04 0« 010 (14 LH) t)4-7(> Kioiii iHirtifH fiii'iiiHhing tlic on-. iy-m 4 lit; 02 04 07 OIK! 57-50 ti2 0 THE SMKM'ISO OF TITANIKKROUH IHON ORKS. u:\ ,T I size sutHciently larm' it a certain treatment that, if we were suc- , reduction of the ores, sfactory and especially irnvided with motlern ssary to coinplicate the mplicity and economy not in sucli circiim- B of blast ; in short, wo unfavourable. But as possible the relative [1 non-titaniferous ores, Krst on ordinary ores, itudy its workin}? And iduction, quality of pi^- metal before we should we iiecured, we l)elieve, le economy of smeltiny nent of the same ores, I in both cases we were as to apparatus used, ials which entered the lemist in charge, sup- had made by diffeient nishcd to us by outside // '^Ollrili f/iisHidftritiiii). riieiiUKt in clinrKc SiO 2 Wt (.'iiO' iVJ(H» Al.jO, ori!» Mko i.ittif. Connilttville Oikr, ("JW (levocnt ivhIi.) f'luiiiisit ill cliar^c. S Si< ), . . Al.O, Cni) . »7x 3 III) rs2 1 .-HI ti; Ihickeltiitoivn, X. J,, Dolomite, Si( ),j TaO . A1,0„ Fc.o.. K. S. Motfat. S (Mi LX.I (Kl 1 l-J IS 57 riiilailrl |i)iia Iron Workn. !t 44 •J81S 4 It; 15 35 Lafavt'ttc Colli'jti-. !l 27 29 2! » 337{ 17 »• AvcniKi' analysii liy the writi r at lluiintciii, N. A . S-75 2S CO 3 (H» 7<> It; {Ml IHS. 15P.,Oj Titaniferous Ores of the Adirondacks (Ease.)- County). " Mii.i I'oMi." " Sankoho." •'ClIKNKV." i X Clioinirit ill cliarge. -g i .Middling Ijoih 1 ore. t % & ' S". 4J '^- . ""J ri 1 X a" 2-46 S CS 3 •lb SiOj.... 10!t 3 ((7 1.53 87 1 39 1 34 9-79 TU) 10 73 i3:w 19 74 10 111 20 03 19 52 18-70 8-25 15-77 Al.,0., . . 44 vm 3 50 53 3 50 4 00 .... 7-12 f'nO tract's, traces. little. omt little. 1 (iO 8-S9 3-ipe is (i inclies indiau'eter, taking the blast from a .system of two parallel rows of (J-inch diaincHer iron siphon-pipes arranged in an oven htjated by a coke (ire on a grate at one end. With this arrangement we have not been abh; to obtain practicallj" more than 400 F. as tempenitur(i of blast measured at the tuyere's noz/.le. Tiie tuyeres, three in iiumlicr, take the blast from the circle pijie through 3-inch diameter droj) pipes having a diameter of 2 incluis at the nozzle, wiiich could be reduced by means of propei' bushings, if found advisable, to all dimensions from 2 inches to 1 inch. Tiie tuyeres are provided with iron coils fitting them loosely, and where this coil passes through the liack lining the latter was replaced by a special cast iron hollow box taking the circular shape of the fur- nace, and allowing the coil bearing the tuyeres to pass freely through a circular opening in the box, this opening and the space betwt en the coil and tuyere being rammed in with tire-clay during the run. An independent circulation of water through the coils and boxes insured the cooling. In order to protect the boshes we resorted to a simple special device which proved very satisfactory. I used thick sheet iron plates made to fit snugly the curve and slant of the boshes between tOAMI, J TIIK 8MKLTIN(i OK TITAMKKHOUH IRON OHK8. 17') .1 ono-lifth to one sixth o pooror «)r(', this last (l(«(lly striititietl rocks, Ims almost ulontifa'ly Hock ami Lako Oliain- analyscd by PiotVs.sor saino formation, if wo ■ oology at Ooliimlna lish at an early (late UK of tlif titatiiftTous l)ott(mi of tho lioartli il)l(> is "J tVi't ti iiu'lu's, iimotcr 4 fwt ('• im-lips li a diameter of 1 feet Pact 10 ioehes to IJ feet ; tlieu vt-ry ne;iily 200 15. furnaeo rire-lnicks '.) lifs, iiiakiiif,' tlie total iin six east iron jiillars ;tiii;j on the masonry of r rin^' supporting,' the takinf,' the hlast from a cter iron siphon-pipes rate at one end. With it;iin practically more iit the tuyere's nozzle. ;t fnim the circle pipe meter of 2 inches at of proper ImshinRs, if to 1 inch. ing them loosely, and the latter was replaced •ular shape of the fur- to pa'is freely throufjh the space l)et\v< en tho during the run. An coils and boxes insured resorted to a simple I used thick .sheet iron of the hoshes between the pillars. These plates were upset at the Imttom so as to form a shallow collector for water, clo.sed at lK)th ends. The water, supplied by a circular pi|>e around the furnace, sprayed through pin-hole open- iii'js provided for the purpose on the inside of this fe<>d pipe and trickled down in tine streams on the inclined surface of the plates to tiie collector at the bottom, to be there wasted Tlie blast was supplied by a positive rotary blower capable of deliv- ering at a normal speed at least 1000 feet per minute ; more or less could be obtained according to tho speed of the small st(>am engine • hiving it. The delivery pipe was inches in diameter. Where it entered the liot blast oven it was provided with a release gate valve to control the volume and pressure of air admitted in the furnace. In no ease was the volume above otJO oubio fe(!t per minute; generally from '.\')0 to too cubic feet under a prtissure of 10 to 20 ounces (1 to 1 1 pounds). In order to meet p ssible contingencies a by-pass vvith special arrangement of valves connected the adinisHion pipe and deliv- ery pipe of cold and hot uir, so that in ca.se of accidents happening to the oven we would hive bt-en able to blow in with cold air during the i'cp;iirs ; but we did not have occasion to use it. It was s(ion found that by driving the furnace fast the best results were obtained. The slags, to our surprise, considering the small height of the furnace, did not contain much iron, no matter whether- the ores used weie Lake Superior hiematites or titani^erous ore<. Bydri\ing slowly the percentage of iron in the slag could be kept below 2 per cent (2'G() per cent FeO at most), a very small amount indeed. The slags of the large Dowlais furnaces, as stated by Peicy, carried, in his time, 2 oO FeO, and not UMfre<|uently I oO. ") .'»0 per cent Ket), and even 7 and 8 per cent in running as while iron. At the Kbbw Vale and Blaena Iron Works, says the same writer, the regular amount of iion carried by the slag reaches ."> per cent or more, or Cy'A) to 7 per cent Vt'O ; it was exceptionally that we had mort; than this, and we may .say that prac- tically, in our condition of running, the reduction of the oxides of iron was quite .satisfactory. As could be expected, the furnace was extremely sensitive to any sudden changes in the burden, as well as to disturbances or irregu- larities in the amount or pressure of blast. On the other hand, it answered (juickly to any such changes, and some 15 hours after the charges had been niotlitied, sometimes less, the expected slag was tapped. Numerous analyses proved this to be the case. This feature of the apparatus was very advantageous for our purpose, as it allowed us to experiment on almost any composition of slag desired and ascertain rapidly the effect on the running of the furnace. I 176 J yUEBEC. It could be easily observed also that, though the heat in the furnacf were sufficient for a satisfactory reduction of the oxides of iron and the melting of almost any slag, it was not high enough to reduce the silica and cause the metal to charge itself with silica and graphite carbon. The iron obtained from botii kinds of ores, titaniferous or not, was invariabh' whiti, and still during our run with Lake Superior hivmatites, not containins; any titanic acid, we so proportionerl our charges purposely to obtain slags so basic and so aluminous that some of them would have appeared, o priori, to be only admissible in fur- naces in which the u'reatest heat prexails. Their composition corres- ponded to that of slags accompanying the darkest grades of iron, most charged with silicou and graphite, obtained in furnaces in which the temperature of tlie blast reaches as high as 1400 degrees F. and its pressure 8 to 10 pounds. Under these conditions of working, no titanic acid could be reduced. We made a great many analyses of slags during this run. No. 1, with non-titaniferous hicmatites, their average oxygen rutio being over 4:4 (1 : 1), and we ran slags extra basic of a ratio of 4 : 6 (1 : 1.^), and still the iron was white. We quote as types the following : SK)., : M Cab '. ;«•«" .30S0 2«t(.27 M(rO 4 ;« 4"0 4. 5 to 5 FcO :iso am 280 to.') 0.\ygcn ratio 4 : (1 4:5 4:440to4'44 In this run we used as limestone the calcite of which the analysis has been given above, adding generally a little dolomite, of whi:h we had a large stock. The greatest run made in 24 hours with these ores, which contained an average of 62 per cent of iron, was 4600 pounds. These hivmatites were not reduced as fast in the furnace as we expected they would l)e ; driving fast increased the production but not to tne extent looked for. The blast was kept at a pressure of an average of 16 to 18 ounces, its volume fluctuated between 350 and 450 cubic feet. When we had ascertained what we could expect from our furnace with ordinary ores, we l>egan to add the titaniferous ores mentioned above in the proportion of four-fifths to five-sixths of Mill Pond or San- ford, and one-fifth to one-sixth of Cheney. It had not been the in- tention to use this Cheney ore at all at first, but owing to .some mistake at the mines we had to dispose of some 40 or 45 tons of it. We pro- ceeded by gradual increases of one eighth titaniferous ores in the kt in the furnacf idea of iron and ;h to reduce tl-e ;a and graphite titaniferous or h Lake Superior roportioned our inous that some tnissible in fur- iposition corres- lc8 of iron, most jes in which the jgrees F. and its of working, no nany analyses of hu'matites, their ran slags extra Ijite. We (juote 3«i to 37 2S til 27 4 5 to 5 (» 2 80 CO 5 4:4 40to444 ich the analysis lite, of whi .*h we which contained These htvnuitiU's d they would l)e ; xtent looked for. to 18 ounces, its rom our furnace ores mentioned klill Pond or San- not been the in- l to some mistake of it. We pro- ous ores in the J THE SMELTING OF TITANIFEROUS IRON ORES. 177 J charges, keeping the furnace a certain time on each new mixture, until the burden of ore was all in titaniferous ores. During this run. No 2, the mixture averaged 55 to 56 per cent of iron. Our best run in 24 hours was 5035 pounds. As will be noticed, as soon as we began to charge the titaniferous ores the yield of the furnace increased to a decided extent. It appeared as if these ores were more readily reduced than the hunnatites, made iron faster, at least under the conditions under which we were working. Large lumps not being admissible with a tunnel head 2 feet 10 inches to 3 feet in diameter, we broke all our stock, ores and flukes, from beginning to the end of the tests, to pieces of the size of the fist or a very large egg. The pressure of this blast during this run — No. 2 — was about the same, 1 7 ounces on an average, and its volume varied, as before, between 350 and 400 cubic feet. During this run we changed our stone from a calcite to a dolomite, or rather a dolomite to which we added enough calcite to bring the percentage of magnesia in the mixture of stones to about 12 to 14 per cent. We give l)elow the principal analyses of the slags run as types : AtVH'gin- Middle of Toward cud iiin^. run. of run. SiO., :M10 2<)-.'J0 27-29 TiO.. 4 90 9-9(! 1748 AljO:, 220(» 18-2(i 14-43 OaO 23 t)3 24 12 22-71 MgO 10-(K) 9 72 1155 Ft'O 3 82 (i-40 4-.S0 Oxygen ratio 4:440 4:410 4:350 When the furnace was fully on titaniferous ores, the ore mixture averaged about 52 per cent of iron. It was soon noticed that the furnace could be driven fast with great advantage. A charge would reach the bottom in less than 15 hours; 12 to 15 hours was the rule. The yield increased considerably. We had runs of 4800, 4900 and 5600 pounds in 24 hours, and our best run in any single day reached as high as 6735 pounds, fully 3 gross tons. The blast was kept at very nearly 18 ounces throughout ; it did not vary to any extent, and the only changes observed were independent of our control. They were due to the irregularities in the blowing apparatus, which, owing to the exigencies of the works where these experiments were made, had to be located at a considerable distance from the hot blast oven. The economy of running the furnace fast was clearly apparent and confirmed our views in this respect, views corroborated by A. Pourcel, late technical director of the steel works at Bilbao, Terre Noire, 12 ii '15 178 .1 QUEBKC. Fi'ance, and Port Clarence, England, in a letter, from which we extract the following : " Mr. Rossi's ideas concerning the treatment of titaniferous ores in the blast furnaces have struck me from the start, as you are aware, as eminently logical. Furthermore, they seem to me to be sufficiently justified by the trial, on a small scale (in 1893), which Mr. Rossi has described in detail. * * * The easy reduction of the titaniferous ores justifies the expectation that with a blast furnace of 300 ccm. (10,500 cubic feet) capacity, for instance, it will be possible to reach easily a production of 100 tons of pig iron in 24 hours with ores con- taining 52 to 56 per cent metallic iron. * * * In conclusion I will say that the formula of slag and of moderate temperature of blast (300 to 400 degrees C.) recommended — with proof to sustain his opinion — by Mr. Rossi, ought to ensure the success of the treatment of titaniferous ores from the start, but there is nothing to exclude, a priori, the hypothesis that, with a rapid driving, by forcing somewhat the production, it may be possible to produce the same forge iron or pig iron for open hearth steel (Siemens-Martin furnace) with a temperature of blast higher- — that is, in the conditions of running economical as to fuel. * * * " In order to judge of the relative ectmomy of these three runs, under as nearly as possible similar conditions, we will compare the amounts of fuel and stone re(|uired per unit of pig metal when the furnace gave the greatest jiroduction in eacli case. This supposes indeed, for the kind of ores or mixtures of ores ccmsidered, the most favourable conditions of running for eacli. liy making precisely the same ample allowance of time in each case for stone and coke before each maximum cast of 24 hours as chargeable to that cast, we found the figures given below. AVe feel justified in doing .so by the fact that with titaniferous ores we had two successive casts of 12 hours each of 3325 and 3410 pounds (in all 6735 pounds in 24 hours) followed by a cast of 3200 pounds, and in other runs a cast of 2400 [X)unds in 12 hours followed by one of 2635 pounds (in all 5035 pounds in 24 hours), for the mixture of titaniferous ores and Iwrnatites, and a cast of 2200 pounds followed by one of 2400 pounds (in 12 hours), in all 4600 pounds in 24 hours, for the non-tituniferous hiematitcs smelted alone. Riiii No. I. -N(in-tittuiift>i'le a small salamander, re visible either in the nace. This could be 'nace were not such as acid. Though much pted (a temperature of these ores), they were with these ores, have lined but 1 to 02 >f titanium. Far from hes, and the latter was il. We made a great run ; others have been aost characteristic ones [5 .S2 n 2('. l4-5(» {0T)6 !»■(»!) n |iii|)ci'. (-.r-t 5i . '«• . h At : • 182 J QUKnEC. not our intention in this article to examine the causes of this super- iority. In a general manner we may say that if it is due to tlie presence of titanium in the pig metal, very small quantities of this substance are then sufficient to secure such results. In our blast- furnace tests we have not been able to obtain more than a few hun- dredths to one tenth of one per cent of titanium. It is met in quantities varying from 0-2 to 1 per cent in many pigs here and in England, to which it seems to impart a "greater tenacity."* The higher the grade of the iron the more titanium it is likely to contain. On the other hand, titanic pig made from ores from St. Urbain, Canada, containing as much as 41 to 48 per cent of titanic acid, smelted by the Forbes treatment under low temperature and pressure of blast, contained only traces — 0'03 to 005, exceptionally 0-26 titanium — and still the qualities of the pig metal and iron were "exceptionally good " (analyses made at the Paris School of Mines). But, if but comparatively very small amounts of titanium and silicon are found in the pig metal from a cold furnace, the percentage of carbon, mostly in the combined state, is often very high. Analysis of the metal from our small coke furnace of 1893 gave : — .Silicfm o:«» tract'M to 016 Titanium None 007 Comb, carbon 2H3r) 2mt ( Jraphitic carlxjn 0253 24 Even the salamander contained only Si, 1'05; Ti, 0*054. The metal, though " white," has not the ordinary charactere of white iron. Its grain is generally very close and fine, its fracture more steel-like in colour and appearance and it is remai-kably tough and hard. Under special conditions we have obtained pig metal containing : — Silicon 2it 062 and even 84 Titanium 085 078 I'M ManganeHe 034 .... Carbon 4m 412 It was so hard that it could hardly be broken on an anvil with a sledge hammer. It blunted the hardest drills and we had difficulty in obtaining samples for analysis. Having been called upon by a large manufacturing firm to make tests on the chill, strength and resistance of mixtures of cast iron into which entered small percentages of different metallic elements, we had occasion to test, on the machine, our white cast iron obtained from titaniferous ores. Square bars of 1 inch section and 12 inches long Itetween supports, broke under a load at the centre of 2700 to 2900 * Rivat Deciiuasiu, p. 100. 1 causes of thia super- it if it is due to the nail quantities of this results. In our blast- more than a few hun- inium. It is met in any pigs here and in eater tenacity."* The it is likely to contain, nni St. Urbain, Canada, «nic acid, smelted by and pressure of blast, Uy 0-26 titanium — and ) "exceptionally good " unts of titanium and urnoce, the percentage n very high. Analysis 93 gave : — ) ;«5 traccH to 16 S^ne 07 ! K3o 8-99 )-25S 0'24 05; Ti, 0054. The laractera of white iron, cture more steel-like in jgh and hard. Under ontaining : — 62 and even 84 1)78 1-94 112 ken on an anvil with a ,nd we had difficulty in icturing firm to make ctures of cast iron into tallic elements, we hariment can verify, titanic acid can form definite compounds, perfectly fusible, if properly Huxed, containing as much as 35 to 40 to 50 per cent of titanic acid, with alumina, lime and magnesia as bases, and admissible as slags in blast furnace work. Larger percentages still, such as 65 per cent can enter into a compound, and it remains fusible. The objections to the smelting of titaniferous ores on account of the refractory character of the slags are not sustained by our practice, or that of others, oi- by direct experiments on the properties of these compounds. 2. In running a furnace under special conditions of temperature and pressure of blast, no trouble has been experienced from titanium de- posits. We never observed any in our blast furnace tests, and none are mentioned by Dr. Forbes in his practice in England and Norway. 3. If these special conditions of the lower heat, considered more favourable in smelting these ores, are held to imply against them a waste of fuel, it is a question whether this is not ofiPset by the smaller amount of cinder to melt, the lesser quantity of tluxos necessary and their indirect effect on the productive capacity of the furnace, as well as the greater value of the pig metal obtained for specific and numer- ous applications. 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