BY H. I. JENSEN. 107 



(2) The essential minerals are quartz, orthoclase, topaz and 

 muscovite. As diminutive and minute constituents we have 

 cyanite, rutile and zoisite. On account of the abundance of 

 quartz and felspar, this rock belongs to the class of metamorphic 

 rocks termed " Granulites." 



Name : Cyanite-Rutile Granulite. 



Sp. N0.6IA. Granulitic Mica Schist. Loc: Mt. Delaney. 



i. Handspecimen of a metallic grey colour, with a shining 

 lustre and a fine-grained texture. 



ii. (1) Holocrystalline; fine to medium grain-size, schistose 

 fabric. 



(2) The essential minerals are orthoclase, muscovite and seri- 

 cite. Chlorite is present in notable quantity. Magnetite and 

 cyanite are present in diminutive amount. 



(3) The cyanite is pleochroic, from colourless to light blue; has a 

 high refractive index and high double refraction, and is developed 

 chiefly in the crushed felspars. 



(4) Name : Granulite or Granulitic Mica Schist. 



Sp. No. 61B. Muscovite-Granulite. Loc: Mt. Delaney. 



i. The handspecimen has a yellow colour not unlike man}' mica 

 schists, and a schistose cleavage. Crystals of orthoclase project 

 all over the surface, giving the specimen a knotted appearance 

 like knotted andalusite schist. 



ii. (1) Holocrystalline, with variable grain-size and schisty 

 cleavage. 



(2) The essential minerals are orthoclase, quartz and yellowish, 

 slightly pleochroic, muscovite. Notable in quantity are sericite, 

 chlorite and topaz. In minute amount as important accessories 

 we have biotite, zoisite and rutile. 



(3) The rutile forms a felted mass of minute acicular crystals 

 included in the quartz. Under the low power they appear quite 

 black and dusty, but under the high power they are resolved into 

 clear needles with geniculate twinning frequently developed. 



(4) Name : Knotted Muscovite Granulite or Gneissic Mica 

 Schist. 



