PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 625 



i-tj. A tine-grained, dark-green, soft, much fractured rock. 

 No section. 



Age. Keewatin. u. s. G. 



No. 997. GREENSTONE. 



Kawasaehong falls. 



Ref. Annual Report, xv, pages 319, 320, 346, 393; Bulletin vi, pages 39, 421. (Compare No. 356.) 



Mey. Soft, fine-grained, roughly schistose greenstone. There are two speci- 

 mens, one finer grained than the other. 



Mic. The finer-grained section is composed largely of chlorite and altered 

 feldspar. There is some hornblende, quartz and ia</netite. In places, the feldspar 

 takes a lath-shaped form, suggesting that the original rock may have been a diabase. 

 The other section consists mainly of hornblende and altered feldspar. Chlorite, 

 quartz and a gray opaque substance, are present; the last is perhaps an alteration 

 product of ilmenite. 



Two sections. 



A>/e. Lower Keewatin. u. s. G. 



No. 998. GREENSTONE. 



Rapids above Kawasachong falls. 



!;,'!'. Annual Report, xv, pages :ilit, 320, 3! )3; Bulletin vi, pages 37, 39, 40,421, plate V, figure 5. (Compare 

 No. 356.) 



A medium-grained, green rock, composed largely of hornblende. 



Mir. Dr. H. Ilensoldt's description of this section is as follows:* 



"A hornblende-dioryte of similar structure and composition as No. 999, but 

 containing a perceptible admixture of quartz. The hornblende scales are much 

 larger than in No. 999, but their feeble dichroism indicates a more advanced 

 chloritization. The feldspar is exceedingly turbid and has lost its optical properties, 

 no twinning lamellation being perceptible in any of the crystals, but the forms of 

 the original prisms are still preserved. The quartz grains have a fragmental appear- 

 ance and do but seldom show rounded forms; they are small and easily distinguished 

 by their transparency and brilliant polarization. This dioryte contains little if any 

 magnetite, but we observe in the section numerous crystals of titaniferous iron, 

 surrounded by a peculiar grayish-white alteration product." 



One section. 



Age. Lower Keewatin. u. s. G. 



No. 999. GRIOKNSTONE. 



Above No. 998 and near Garden lake. 



Rff. Annual Report, xv, pages 319, 320; Annual Report, xvi, page 111; Bulletin vi, pagos 37, 39, 40, 421, 

 plate V, figure 4. 



"JJultctin ri, p. W. 

 41 



