PETEOQRAPHIC GEOLOGY AND DESCRIPTIONS. 899 



Dioryte. Slate.) 



Mic. This rock is like the last in all respects, but contains more sphene. These 

 grains are usually nearly perfect crystals, though very small, and occasionally one is 

 wholly within a hornblende. One section. 



Aye. Upper Keewatin. N. H. w. 



No. 594aG. DIORYTE. 



Pebbles from No. 594G ; same locality. 

 Ref. Annur.l Report, xx, page 76. 



Meg. Fine-grained, dark, greenish-gray rock appearing like a fine diabase, of 

 granular texture. 



Mic. The slide varies, having on one side apparently a portion of the matrix of 

 the conglomerate. This portion is composed of small feldspars compactly crowded 

 together, more or less decayed, but subsequently regenerated, with occasionally a 

 small hornblende and a small sphene. The rest of the slide consists of the same 

 minerals, but hornblende greatly preponderates. It is also here apparent that the 

 hornblendes are poikilitically embraced in the secondary feldspars. One section. 



Age. Pebble in Upper Keewatin conglomerate. N. H. w. 



No. 601G. SLATE. (Metamorphosed.) 



S. W. % N. W. J sec. 3, T. 64-7, west shore of Kekequabic lake. 

 Ref. Annual Report, xx, page 72 ; Annual Report, xxi, pages 37, 51. 



Meg. Aphanitic, almost flinty, greenish gray. 



Mic. A fine, pulpy mass of feldspathic debris, with a few quartzes. There 

 were a few grains of feldspar that were larger than the average, but they were 

 decayed and macerated before consolidation. Their disintegrated remnants are 

 dislodged and slightly out of place with each other, the interstices having been filled 

 with the finer matrix; yet these remnants have been recrystallized and appear now 

 quite fresh. Their borders throw angular and hooking projections into the surround- 

 ing matrix. The whole matrix is also in a completely recrystalline condition, and is 

 composed of finer feldspars and quartz, with a sparse network or sprinkling of a light- 

 green, non-pleochroic, highly refractive mineral or minerals, which, in high power, 

 seems to be resolved into granular epidote, spicules of hornblende and grains of calcite. 



The rock shows indistinct variations in size of grain as well as in composition, 

 the same that are more conspicuous in the coarser clastic rocks of the region, viz.: 

 Small, angular and roundish areas occur in the midst of coarser grains which are 

 either (1) More abundantly supplied with the darker elements, and between the 

 nicols are so much darker constantly as to suggest the existence of chlorite, or 

 (2) Are almost wholly occupied by finely interlocking granular quartz. These seem 

 to have been originally small clastic masses which differed from the prevailingly 

 feldspathic material, and which, on recrystallization, have been reformed but have 



