PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 911 



Greenstone. Amphibolyte. Tuff.] 



No. 33 W. GREENSTONE. ( Graywaclcenitic. ) 



N. E. M S. W. J4 sec. 14, T. 62-14, northwest part of Sand lake. 

 Ref. Annual Report, xv, page 29. 



Meg. Compact, but finely jointed, tough, weathering like a greenstone. 



Mic. Hornblende, chlorite, epidote, with more or less indistinct feldspar, compose 

 this rock, giving it a green color. The first is in more or less large crystals and parts 

 of crystals, as well as in fragmentary and interlocking shreds which are spread 

 throughout. One section. 



Age. Lower Keewatin. N. H. w. 



No. 82W. AMPHIBOLYTE. 



S. W. J4 N. W. % see. 29, T. 63-12, Long lake. Island north of point. 

 Ref. Annual Report, xv, page 53; Annual Report, xxiv, page 42. 



Meg. Fine, compact, with weathered aspect of a schist. Compare No. 2104. 



Mic. Hornblende and an altered feldspar, with a little quartz, compose essen- 

 tially this rock. The feldspars are nearly dark between crossed nicols, due to a 

 saussuritization (largely of granular and scaly chlorite) which they have suffered, 

 except in an occasional very narrow thread-like border or zone about their periph- 

 eries, which is quite bright and evidently of some other but indeterminable mineral. 

 One section. 



Age. Keewatin. N. H. w. 



No. 83W. AMPHIBOLYTE. 



N. W. "4 S. W. >4 sec. 29, T. C3-12, Long lake. Island close to point. 

 Ref. Annual Report, xv, page 53. 



Meg. Green, feebly schistose. 



Mic. This slide is like No. 82W, but in addition shows considerable hmcoxene. 

 One section. 



Age. Keewatin. N. H. w. 



No. 84 W. TUFF(?) 



N. W. J4 S. W. J sec. 29, T. 63-12, Long lake. Little island near the shore. 

 Ref. Annual Report, xv, page 54. (Compare rock No. 2099.) 



Meg. Fine sericitic schist, holding hornblendes porphyritically. 



Mic. This rock has a strong schistosity. The porphyritic hornblendes are 

 surrounded by a fine saussuritized feldspathic mass, which is nearly dark between the 

 nicols, like the feldspars in No. 82W. These hornblendes are bordered and patched 

 by a second development, i. e., the forms of the original augites are shown by the 

 different coloration of the central portions, these central portions being the latest to 

 acquire the hornblendic composition and cleavage. 



Age. Keewatin. N. H. w. 



