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 sediments 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 S-p. Gr. 



.Quartz 215TX2 



Feldspar . . 

 Pyroxene . 

 Titanite. . . 

 Magnetite . 

 Apatite . . . 

 Zircon . . . . 



775 X 2 



230 X 3 



16 X 3 



7x5 



2x3 



2x4 



65 = 



65 = 



3 ^ 



5 = 



25 ^ 



2 = 



5 = 



Units 

 by weight 



: 5700 = 



: 2053 = 



805 : 



56 = 



37 = 



6 = 



9 ■■ 



Total 3,T^^3 



8666 



% weight 

 65.78 

 23.69 

 9.29 

 0.65 

 0.42 

 o .07 







Composition 



calculated from mode 









Qz. 



Orth. 



Alb. 



Anor. 



Pyrox. 



Tit. 



Mag. 



Zir. 

 & Ap. 



Total 



SiO. 



A120, 



65.78 



2.38 

 0.65 



8.28 

 2.31 



3-45 

 2.94 



5 -04 

 0.30 

 0. 17 

 .62 



1-73 

 1.28 

 0.09 

 0.03 



0.03 



0.20 





.03 



85.18 

 6 . 20 



Fe203.. . . 







0.28 

 0. 14 





0-45 

 0.76 



1-73 

 3.12 

 1.50 

 0.69 

 .03 

 0.26 



FeO 











MgO 











CaO 









i.6t 



. 19 





0.04 



NaaO 







I. 41 



K2O 





0.66 









MnOz 















TiOz 











.26 







ZrOz 















.07 

 .02 



.07 

 . 02 



P,0^ 1 

































Total . . 



65.78 



3 . 69! 12 .001 8 .00 



9.29 



0.65 



.42 



0.16 100 . 01 



