PETROGEAPHIC GEOLOGY AND DESCRIPTIONS. 773 



Dioryte. Greenstone. Syenyte.] 



No. 1734. DIORYTE. (Camptmyte?) 



Sees. 29, 30, T. 64-8, north shore of Snowbank lake. 

 Ref. Annual Report, xxi, page 157. 



Meg. Seems to be a portion of No. 1733; dark gray, fine grained, sparingly 

 interspersed with some crystalline red grains. 



Mic. The hornblende (which is abundant) is partly porphyritic. The feldspars 

 have central areas decayed, but marginal zones of fresh growth. A second develop- 

 ment of feldspar is also dispersed throughout the rock, with quartz. Epidote is not 

 abundant. Differs much from No. 1733. One section. 



Age. Archean. 



Remark. This rock has the appearance of being a massive crystalline one, and 

 as such it cannot be a part of No. 1733 except by reason of more intense metamor- 

 phism. N . H. w. 



No. 1735. DIORYTE (with quartz). 



Forms the coast eastward from No. 1734, and also dikes in No. 1733. 

 Ref. Annual Report, xxi, page 157. 



Meg. Rather dark, with hornblende. 



Mic. Much of the feldspar is zoned and so altered at the centre, and over most 

 of the grain, that it cannot be determined. The later feldspars are oligoclase ( ?) and 

 Hticrodine. Quartz is interlocked with the later feldspars. The hornblende is varied, 

 sometimes but little polychroic, apparently actinolite, and sometimes simply green 

 hornblende, but more absorptive and more polychroic. Epidote, magnetite, chlorite 

 are more or less associated with this varying hornblende. One section. 



Age. Archean. N. H. w. 



No. 1736. GREENSTONE. 



S. W. 14 sec. 20, T. 64-8, Snowbank lake. 

 Ref. Annual Report, xxi, page 157. 



Meg. Dark greenstone, cut by the next. 



Mic. Hornblende, chlorite and biotite, with a little magnetite give the rock its 

 dark color. The rest is feldspar in two stages, viz., much altered and fresh, with a 

 little epidote. The grains are all small and roundish. The aspect is that of a clastic 

 rock regenerated. One section. 



Age. Archean. N. H. w. 



No. 1737. SYENYTE. (Red) 



Cuts rock No. 1736 as dike. 



Ref. Annual Report, xxi, page 157. 



Meg. Weathers red. 



Mic. The rock consists almost solely of microcline and microperthitic feldspar. 

 Some of the feldspar is near andesine-oligoclase. There is very little hornblende. 

 One section. 



Age. Archean. N. H. w. 



