PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 897 



Granite. Conglomerate.] 



proportion of the feldspar fell between a specific gravity of 2.58 and 2.62, which 

 would indicate that the mineral was a mixture of the orthoclase and albite molecules; 

 and the analysis, as here given, shows that it belongs to the anorthoclase series. It is 



SiO 2 A1 2 O 3 Pe a O 3 CaO MgO K 2 O Na 2 O H,O Total 



67.99 19.27 .82 .75 .02 3.05 6.23 .90 99.03 



to be noticed that the silica percentage is larger than is required by the amount of 

 soda, potash and lime present. This is probably due to the fact that a small amount 

 of quartz was so intimately intergrown with the feldspar that certain grains of the 

 feldspar powder contained some quartz. From the analysis it is calculated that this 

 feldspar is an anorthoclase with approximately the composition Or 5 Ab 14 An^ 



Quartz is present only in small amount. Green augite is common. A description 

 and analysis of this green augite is given under No. 1094. One section. 



Chemical analysis. An analysis of this rock gave the following result: 



SiO, P 2 O 6 " A1,O 3 Fe 2 O 3 PeO CaO MgO K 2 O Na 2 O H 2 O Total 

 66.84 trace 18.22 2.27 .20 3.31 .81 2.80 5.14 .46 100.05 



Age. Arch,ean. 



Remark. This rock is a typical specimen of the augite soda granite of 

 Kekequabic lake. u. s. o. 



No. 593G. CONGLOMERATE. ( Granitized. ) 



S. W. M N. W. Y sec. 31, T. 65-6, south shore of the east end of Kekequabic lake. 



Ref. Annual Report, xx, page 76. "On the northeast corner of this point is a low outcrop of a fine- 

 grained, gray, apparently holocrystalline rock. The groundmass is grayish, and in it are small, black needles, 

 probably of hornblende, and a few scattered, rather irregularly outlined feldspar individuals. There are also a 

 few rounded pebbles up to those two inches in diameter, scattered through the rock. The specimens collected 

 (No. 593G) show some of the pebble forms. Some of these pebbles are seen to be subangular, but most of them 

 are rounded. They seem to be scattered irregularly through the rock, and lie in no definite planes or layers. 

 There is nothing in the rock to show any sedimentary lamination or bedding ; it appears perfectly massive. This 

 rock is seen in several outcrops in the N. E. J^ S. W. J4 sec - 31, T. 65-6, and the shore is here usually lined with 

 fragments of it. In the eastern part of this one-sixteenth section is quite an extensive exposure a short distance 

 back from the shore. Here the pebbles, which have been steadily increasing in abundance eastward from the 

 first-mentioned outcrop, are very numerous. It would be almost impossible to find any surface a foot square in 

 the rock at this place which would not contain one or more pebbles, and many areas of this size would include 

 as many as twenty. The rock is here represented by No. 594G, and pebbles from it by No. 594aG. This rock 

 extends along the shore in a few outcrops nearly to the east line of section 31. The pebbles grow less abundant 

 in going east from No. 594G. No. 595G shows a more highly crystalline condition of this rock from the S. E. % 

 N. E. % sec. 31. The noticeable features of this rock are its sharply outlined, rounded and subangular pebbles, 

 and a few scattering, apparently porphyritic, feldspar crystals, sometimes a quarter of an inch in length. No 

 bedding, lamination or definite arrangement of the pebbles could be seen in the rock. It seems that this rock 

 is a metamorphosed conglomerate, and it strongly reminds one of certain facies of the Ogishke conglomerate." 

 17. S. Grant. 



Meg. The rock is gray, of medium but not uniform grain, and specked with 

 white feldspars that are usually mere fragment^ of crystals and with pebbles. Its 

 feel is sharp and rough. While evidently a fragmental rock originally it is now 

 compact, sub-crystalline and massive. 



Mic. The bulk of the rock is composed of feldspar, the most of which appears 

 to be of orthoclase, some of it originally zoned, but there is occasionally an instance 

 of albite twinning. The grains are fresh and even glassy in their translucency 



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