PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 331 



Sericite and chlorite schist. Tuff.] 



Remark. A section of the rock embracing the vein is almost wholly dark 

 constantly between crossed nicols, but affords scattered scales of a highly bi-refractive 

 mineral which seems to be of sericite, besides a little calcite and a few grains of 

 secondary plagioclase. 



It also contains a single microsopic crystal of a rare mineral, viz.: tourmaline. 

 This exhibits a longitudal section whose absorption is very strong, bi-refraction strong 

 and single refraction weak. It is crossed by many transverse irregular fissures, but 

 is otherwise without cleavage. It has a dark gray color, and its elongation is 

 negative, and its extinction parallel. N. H. w. 



No. 853. SERICITE SCHIST. 



"Slate, soft, greenish (talcose or chloritic), from about two miles further up the lake, on the south side. 

 There is not much exposure, but sufficient to show the formation extends to here, at least." South end of 

 Newton lake, at the portage to Fall lake; probably near centre of sec. 3, T. 63-11 W. 



Ref. Annual Report, ix, page 91. 



Meg. Soft, light greenish-gray, sericite schist. Resembles, though more fissile 

 and apparently less siliceous, No. 351. Contains a little pyrite and rusty spots 

 probably from the decay of this mineral. 



No section. 



Age. Archean (Keewatin). u. s. G. 



No. 354. CHLORITE SCHIST (?) 



"A less slaty, chloritic slate, from the same place. The slates here run 8. 30 W., standing nearly vertical, 

 sloping south. Indeed, this direction is about that of the narrow, long lake (Newton) in which the route lies." 

 Same locality as No. 353. 



Ref. Annual Report, ix, page 91. 



Meg. A soft, fine-grained, dark, greenish-gray schist, apparently containing 

 much chlorite. 

 No section. 

 Age. Archean (Keewatin). u. s. G. 



No. 355. TUFF (?) ("Greenstone.") 



South side of Fall lake, east of the falls. Probably in the S. % sec. 17, T. 63-11 W. 

 Ref. Annual Report, ix, pages 91, 92; Annual Report, x, pages 89, 95. 



Meg. A massive, yet coarsely schistose, siliceous light-green, fine-grained rock, 

 with white quartz veins, apparently the same continuous rock mass as at Kawasachong 

 falls (No. 356), but more like a graywacke. The single (poor) section at hand shows 

 a fragmental rock composed of shreds of triclinic feldspar and much semi-opaque 

 material, amongst which can be recognized, with greater or less certainty, epidote, 

 mica and some chloritic mineral. Quartz has been generated so as to embrace the 

 other minerals poikilitically. 



Another section, made by Marchand, shows a general composition essentially 

 of a basic debris, the original elements of which have been much altered. It contains 



