PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 185 



Granite. Anorthosyte. Diabase.] 



Meg. The section from the first hand specimen shows a diabase of medium 

 grain with the pl(i(/iodasc and augite. usually much altered. No lustre-mottling is 

 visible, but the rock is too much changed to show the remains of this structure. 

 The section from the second specimen shows large plates of augite holding the 

 plagioclase laths and small grains of otivine. The rock is quite fresh and forms an 

 excellent example of the lustre-mottled olivine diabases. The olivine and magnetite 

 are grouped in indistinct areas or lines, leaving the central part of many of the augite 

 plates practically free of these minerals, thus causing the mottled appearance of the 

 hand sample. 



Two sections. 



Age. Cabotian. Beaver Bay diabase. u. s. G. 



No. 119. GRANITE. 



High point, evidently near the centre of sec. a% T. 55-8 W. Compare Nos. 127, 520, 519, 526. 

 fief. Annual Report, ix, page 31; Annual Report, x, page 40. 



Meg. A medium grained granite, composed of quartz and pink feldspar. 



Mic. The section shows quartz and feldspar (probably orthocla&e) in a granular 

 aggregate, although the feldspar at times has a tendency to an idiomorphic devel- 

 opment. The two minerals are frequently intergrown in small areas of micropegmatite. 

 The feldspar is highly altered and cloudy, and in places has no effect on polarized 

 light. On account of its highly altered nature no attempt was made to determine 

 its species, although it is most probably orthoclase. Some magnetite is present; also 

 much disseminated hematite. 



One section. 



Aye. Cabotian. 



ReiiHn-lc. This is considered a phase of the "red rock" of the region, u. s. G. 



No. 120. ANORTHOSYTE. 



Beaver bay. Probably at west point of the bay. See No. 637. 



Ref. Annual Report, ix, page 32; Final Report, vol. i, pages 196-199. 



Meg. A coarse-grained aggregate of gray plagioclase. It is somewhat altered 

 and reddened in places. No other mineral is present. 



Mic. Similar to No. 113. 



One section. 



Age.. Cabotian. Gabbro. 



Remarks. For chemical analysis and description, see under No. 637, which 

 represents the same rock as this number. u. s. G. 



No. 121. DIABASE (with olivine, coarse). 



West side of second small bay above Beaver Bay entrance. 

 Ref. Annual Report, ix, page 32; Bulletin, ii, page 77. 



Coarse augite crystals embrace tabular crystals of plagioclase, but rather in the 

 form of a mosaic than in the ophitic manner, /. e., the plagioclase is in so large 



