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found in rocks of the KeeWatîn and

NOTES

Three éditions of the map of the Porcupine Gold Area on a scale of one mile to th© inch, have been published. The third édition. No. 21a covered in a general way an a r e a 36 miles east and west by 18 miles north and south, including 13 townships. Owing to the scale of the map, it was impossible to ee^araw rocks of différent c h a r a c t o r which occur

and Shaw townships, a n a t t e m p t lias been m a d e to separate the rocks in much g r e a t e r détail.

The Porcupine area, is s i tuated on the Hudson B a y slope of northern Ontario thenontJierly border of the great c lay boit. T h e principal towns of the a r e a a r e Timmins, South Porcupine and Schumacher . Timmins, by rail is 486 miles from Toronto,

The a r e a is ONE of low relief. hills seldom rising more than 50 feet above the surrounding country. The highest point 1R the immediate vicinity of the gold deposits is on a basait hill ju^t southeast of the •Vipond mine. T h e top of this hill Is l,235 feet above sea level. Stratified clay with some boulders occurs frequently in the lower parts of the area . -whereas some of too higher parts a r e covered with sand and gravel .

GEOLOGY

The legend accompanying the map g ives the rock relationships which have been recognized in the field.

K E E W A T I N . — M o s t of the rooks belong to the Keewat in . These are mainly of volcanic origin, rocognized by the fréquent occurrence of the Pillow l a v a or ellipsoïdal s tructure and am>'gilii1oidaI t ex ture These rocks are very highly altered, and In most cases i t is impossible to definitely name the rocks from which the altered ones have been derived. Probably most of the pillow-lavas were originally basait or nome other basicvoloanic rock•while other rocks aB8ooin.ted with the pillow lavas have been derived from dacitio o r rhyolitic types. T h e volcanic rocks have been intruded by diabasic and dioritic rocks which a r e now so intermingled with the older rocks that they cannot be separated. Examples of these can be observed jus t south of Gillies lake and along the northeast ridge in Tisdale township. Pillow lavas can be convenîently seen on the Millerton claim south of Miller lake and j u s t southeast of the Dome mine. Lavas showing large amygdules and broad ellipses occur on the hill directly east of the Hollinger mine and a t numerous places from the Vipond mine east to the Dome mine. Volcanic fragmentai rocks are rare in Tisdale township. but certa in fragmentai rocks immediately north of the Porcupine Crown mine m a y represent a ^ l o m o r a t o interbanded with the

In the townships of Whi tney , S h a w and Deloro there a r e fréquent outcrops of volcanic fragmentai rocks which a r e interbanded with pillow lavas and iron formation. The series suggests a succession of volcanic rocks (lava, agglomerate and ash) reprefienting periods of volcanic act ivity, and iron formation and associated rocks representing periods of <iuie«oence The icon formation, frequently called ja^nilyts, consiste of interbanded magnet i te or hémat i te with reddish or greyish fine-grained silica.

Owing to the extreme alteralion of m much of( the Keewatin rocks, they a r e most çonveniently referred to as "carbonate s c h i s t chlorite schist, sericite schist, and so forth. the descriptive word depending on the most prominent of the s e c o n d a r y constituents. Many of the rocks are rusty weathered owing to the presence of considerable iron, not only in the lime-magnesia-iron cabonate but in the dîsseminated iron pyrites.

T I M I S K A M I N G S E R I E S . - T h i s n a m e has been applied to a prominent seriea of sédiment* Oonsi^ting of beds of conglomerate, greywacke and slate, and quartzite, which are in almost vert ical att i tude. Thèse rocks a r c now altered ta schist and contain considérable carbonate At the Dame mine and along the ridge to the northwest of the Dome Extension mine there a r e outM^sps of a basai conglomerate which lies unconformably on the volcanic series of the Keewatin . the conglomerate carrying numerious fragments of the underlying séries. A similar condition has been observed at the Three Nations mine where fi-n^nients of pillow lava occur in the conglomerate. Here, however, the rocks have been folded so that the l a v a now overlies the conglomerate a t a high angle.

Q U A R T Z P O R P H Y R Y -This rock intrudes both the Keewat in and the Temiskaming séries. I t o c c u r s generally as irregular masses having ellipt ica l outcrops with the long axes In a gênerai N.K. and S.W. direction. I t is often extremely schistose. similar to the older rocks, and has been subjected to the same vein forming influences, J u s t south of the open pit a t the Dome mine a contac t between the quarts porphyry and t^e sedimentary rock of the Timiskaming shows the quart» porphyry cutting across the sedimentary series. T^e porphyry is intermediate in composition, as shown by the following analysis of a specimen from the outcrop south of the Dome tmne:-Si l Ica67 .64 , alumina 18.HS, ferrie oxide 1.S3. ferrons oxide ï.38, lime 0.39. magnesia I.IU. 3oda *.1B potash 1.60. wa t«r l.fl2, sulphur 1.71 per cent.

S E R P E N T I N E . - S o m e large areas of this rock occur in the southwest part of W h i t n e y township and in other parts of the area

GRANITE POrPHYrY.—One boss-like mass Of the rock oùtcrops on lot 8 in the first concession <d Whitney . I t is fairly coarse in grain and contains much biotite. Narrow dikes of a similar rock

Intrude the serpentine previously mentioned,

Q U A R T Z D 1 A B A S E AND O L I V I N E D I A B A S E .The yauiig^st moka in the a r e a a r e basic, coneistlng of dikes of quartz diabase and olivine diabase. Thèse rocks a r e distinctly later in a g e than the ore deposits. since they a r e known to eut the ore-bearing formations a t the Dome mine and elsewhere. They a r e probably of Keweenawa a ^ . F r o m au examinat ion of the map il will bo seen t h a t the diabase dikes shown in .Shaw and Doloro have been considerably faulted. As the veins a r e much older than the dikes, they would also be subjected to faulting as has been proven in the development of ore bodies a t severa l properties where strong thrust faults have b e ^ encountered.

ORE DEPOSITS

Outcrops of quartz and mineralized .schist occur in many parts of the area . The gold.bearing depositsTimiskaming séries, in the quartz porphyry. and also in the feldspar porphyry. I t is likely that the deposits were formed in Algoma « m e s , following the intrusion of masses of grani té into the older rocks. L a r g e batholîths of granité occur "in areas surrounding the Porcupine area and thèse rocks m a y be represented by the feHspar ami granito porirfiyrieH, Tlie quart?; lias been depositod fronj the impure wat*-.rs which, highly heatcd and under g r e a t pressure, workcd thc ir way through the older rocks , M a n y of the velns have characterist ics of pegmatites, frequently shovrtng feldspar, while the pr imary quartz under the microscope resemblea t h a t o! granité rocks showing gas hui>lilcH and liquid inclusionii. Touitoal ine is prtiaeni in some of the veins^ indicat^Tw a high t e m p é r a t u r e of îormaiion. Th'crc îs évidence m some cases of no definite fiastmiiigi while there are indications t h a t tlie mineraUzed solutions were forced thtough weukened sones »nd the o r e replaced the counti-y rock

There ie prenl. variation in t h c form of the deposlw. When tho onclosing rock i svery schistoso and fohated the quartz masses m a y be lenticular, afl in some doposits a t the M c i n t y r e mine. Again, the quartz m a y be well defl n ed o ver se veral hundred foot, a t tlie Porcupine Crown and Kea mines. Occaaionally uin^ises of quartz have « width of over a hundred fcct JIH in tho original "dômes. now mined, which occurred a t tho Dome property. T h e ore bôdies have frequently considérable length, as . fop e x a m p e. No. 1 vein on the HoUinger, which, on the axi foot level, was traeed for over IMIO feet with an avei-age width of eight feeL liy tho t « r m vein i« inoant a d ^ o s i t , which in iKirta m a y be represented by q u a r t / and in other parts by quartiS and iiiterbandod schlst. the whole deposit being fairly linear. The best deposit* occur in rocks which a r e quite schlstose. where th© mineralization oiMMira over a grea ter width than in the m o r e masHive formations.

T e i n s in which aokcr i te forms a considérable proportion occur in parts of the area as a t the W e s t Dome mine and the Powell claim (M.E 22) in Deloro township, Here the ankerite containa numei-oufi trahsverse stringers of quartz which frequently eaiTy some gold.

The schistose rock adjacent to the voius is often imprcgnated with iron pyrites to a grea ter e s t en t than the veina themselves, and a t most of the mines some of the wall rock eontiguous to the vein ÎH mined as ore.

Both in tbfi fiold and when exaniineil under tho micioacope tho original or priimxry quartz can be observed to be greatly fractured. and a g r e a t part of th e ço ld has been deposited from solutions which have circulated in thèse crushed areas The gold in frequently deposited along dark etreaks of scricite, clilorittt, calcit©, pyiite and other seoondary minorais, and around irregular patchen of dark minerai in tho ijuart/.. The oarilacL uf tho quartz and the schist is also a very favourable location for the précipitation of the gold. In ail the principal depcffiits there is considérable carbonate in the form of caicite, dolomite, and ankerite. The best (loii.litiona for the occurrence of the gold a r e thosa where there ia secondary silification accampaided by a déposition of ii-oii pyrites.

The following minerais have been recognized in gold-bearing deposils in difTerent parts of the area:—Quartz of several générations, oalcite and otlier carl>ouat©s. sericite, chlorite. feldspar. tourmaline and seheslite ; pyrite, cha]cj>pyrite, pyrrhotlte, galona, aine blende, urstmopyritc and hessite.

The gold production from Porcupine is shown in the foUowing table ;

Teni Ounoes Value

1910 1 ,»7 « 3Sfi3Si

1911 766 1 5 ^ 1913 88,72e 1 . 7 3 0 ^ 1913 307,748 4 ,2« . l ia 1914 351,131 fi.l90.7M 191Ô (9 monthfi). 266.993 5.29Ô.086

T o t a l . . . 801,308 J 1 8 , 5 6 1 ^

P R O V I N C E o r O N T A R I O

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