PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 



659 



Tuff. Esterellyte.] 



No. 1093. TUFF. (Green schist. ) 



Southeast side of sec. 29, T. 65-6. Point in Kekequabic lake. 

 Ref. Annual Report, xv, pages 369, 397. 



Meg. Greenish gray, nearly homogeneous, basaltiform. 



Mic. Fragmental debris, consisting very largely of hornblende and feldspar, with 

 a little angular quartz in a matrix of finer materials of the same, with a few grains and 

 groups of epulote, The last is also quite abundant in the form a finer powder in the 

 matrix, but rarely being coarse enough to show its polarization colors. There is a 

 large amount of very fine isotropic substance, apparently of chlorltt'. One section. 



Age. Archean (Keewatin). 



Remark. The hornblendes do not show secondary growths. N. H. w. 



No. 1094. ESTERELLYTE (?) (or Dncyte). 



At the corner of sees. 29, 30, 31, 32, T. 05-6, Kekequabic lake. 



Ref. Annual Report, xv, pages 308, 397 ; Annual Report, xvi, page 100 ; Annual Report, xvii, pages 197, 

 205 ; Bulletin vi, pages 41, 122 ; see, also, Annual Report, xxi, pages 41-49. 



* 



Meg. A hard, gray, porphyroidal rock, not evidently bedded or banded. Com- 

 pare Nos. 1061, 1399. 



Mic. Similar to some already described at Kekequabic lake. Extinction on 

 feldspar 28 on n t , acute bisectrix, indicates labradorite. On another grain extinction 

 on n f is 22, indicating labradorite and on another 29, indicating the same. There 

 is also some microcline, at least a microcline twinning. The larger crystals of the 



labradorite are zoned and composed of different species. 

 Sometimes the fresh central area extinguishes with the 

 external zone, the acute bisectrix being K , at an angle of 

 9, indicating andesine. Sometimes two feldspars are 

 minutely interleaved like microperthite, theinterstructure 

 being parallel with the exterior of the crystal, as shown 

 by the adjoining sketch, which shows a section nearly 

 parallel to the brachypinacoid. These feldspars are also 

 twinned in a complex manner. They sometimes include 

 little crystals of augite, which are also more abundant in 

 the surrounding rock, and are of considerable size, occa- 

 sionally breaking the boundaries of the feldspars. These 

 are fresh and idiomorphic or 'fragments of idiomorphic 

 crystals. Scattered through the finer matrix are also 

 numerous (uihioliff spicules, but these have no apparent connection with the augites. 

 In this rock is also some secondary <//iniiz, some upliciic and some apatite. Two sections. 

 Remark. That these augites and labradorites did not grow up together in the 

 place where they are now found, is evident from the fact that their boundaries 



KIO. 41. TWINNED AND ZONED 

 FELDSPAR IN BOCK NO. lU'JJ. 



