18 Canadian Record of Science. 



inclined extinction, and, when the cleavages are at right 

 angles, are isotropic and exhibit in convergent polarized 

 light a uniaxial figure, which, with the mica and gypsum 

 plates, is seen to be negative. In many cases the scapolite 

 is surrounded by a colorless border, from which, in 

 ordinary light it cannot be distinguished, but which between 

 crossed nicols gives aggregate polarization in bright colors, 

 yellows and blues, and which may possibly be a ■ ' lamellar 

 aggregation of kaolin and mnscovite." x The epidote occurs 

 in lath-shaped individuals which are irregularly cracked. 

 The mineral is nearly colorless, but slightly pleochroic to 

 pale yellow ; extinction is parallel. The refractive index 

 is high, causing it to stand out from its surroundings with 

 a dark border, and giving to the surface a roughened 

 appearance. The double refraction is also strong, polar- 

 izing in high colors. Calcite occurs in irregular individuals 

 of good size. It is somewhat turbid, often shows rhom- 

 bohedral cleavage, and is sometimes twinned. It has a 

 high double refraction which causes it to polarize in silvery 

 tints. The augite is light green and very slightly pleo- 

 chroic ; cleavage is imperfect. In the basal sections the 

 cleavage lines intersect nearly at right angles ; in the 

 orthopinacoidal sections the extinction is parallel ; and in 

 the clino-pinacoidal, inclined, the maximum angle being 

 43.° Hornblende is much less abundant than the augite. 

 It is green, though not very deep, in color, exhibits good 

 cleavage and strong pleochroism, the absorption in the 

 three types of sections being as usual, the maximum 

 extinction angle recorded was 27.° The sphene is rather 

 dark brown, slightly pleochroic, and much cracked. It 

 occurs mainly, along with a few grains of ilmenite and 

 numerous distorted crystals of apatite, included in the 

 plagioclase. 



In general the grains of this rock have a smooth, 



1. Rosenbusch, H., "The Microscopic Physiography of the Rock-making Minerals," 

 Trans. Iddings, 4th ed., 1S98, p. 157 





