GEOLOGY OF THE LONG LAKE QUADRANGLE 



509 



As so modified the analysis falls closely into line with the preceding, 

 though representing a much more impure sandstone, somewhat 

 more shaly, and much more calcareous than the more quartzose 

 rocks. It seems quite clearly a member of the same group. 



Just north of the Bog stream, near the west edge of the quad- 

 rangle, quartz, pyroxene, feldspar gneisses occur which appear less 

 distinctly like sedirrents in the field, and have somewhat the look of 

 the ordinary gneisses. But portions of the mass are excessively 

 quartzose, and in thin section all resemble the Grenville quartzites 

 just described. The slide of one of the more quartzose portions 

 shows a quartz, feldspar, pyroxene rock with small amounts of 

 titanite, magnetite, apatite and zircon. Phlogopite is lacking, and 

 the rock is firmer, more glassy looking and less granular than the 

 usual quartzites. The microscopic analysis however shows a close 

 relationship. 



Mode of quartzose (Grenville) gneiss (6-B-2-a) 



Units measuied Sp. Gr. 



Quartz - 2151x2 



Feldspar 775x2 



Pyroxene 230x3 



Titanite. . . 

 Magnetite . 

 Apatite . . , 

 Zircon . . . 



16 x 3 

 7x5 

 2x3 

 2x4 



Units 

 by weight 



5700 : 



2053 ■■ 



80 5 



56 



37 

 6 



9 



% weight 



65-78 

 23.69 

 9.29 

 O.65 

 o .42 

 o .07 

 o . 10 



Total 



3^3 



8666 



Composition calculated from mode 





Qz. 



Orth. 



Alb. 



Anor. 



Pyrox. 



Tit. 



Mag. 



Zir. 



& Ap. 



Total 



Si0 2 



A1 2 3 .. . . 



65.78 



2.3.8 



0.65 



8.28 

 2.31 



3-45 

 2.94 



5 -04 



0.30 

 0.17 

 . 62 



i-73 



1.28 

 .09 

 0.03 

 0.03 



. 20 





. 03 



85.18 

 6 . 20 



Fe 2 3 







0.28 





0.45 

 0. 76 



i-73 

 3.12 

 1.50 

 .69 

 .03 



FeO 











0.14 



MgO 















CaO 









i.6t 



. 19 





. 04 



Na 2 







1. 41 



K 2 





0.66 









Mn0 2 















Ti0 2 . . . 











. 26 







Zr0 2 :. . . . 















. 07 



. 07 



P 2 O s . . . 



































Total . . 



65-78 



3 - 6 9 



12 .00 



8.00 



9.29 



O.65 



O .42 



. 1.6 100 .01 



