LADAKH, NORTH-WESTERN HIMALAYA. £ig 



a soda-zoisite. Its optical characters agree with zoisite. Part of it 

 is clear and transparent, but here and there it is clouded and opaque. 

 Its double refraction is feeble, and often it has no action on pola- 

 rized light. Its refraction is high, namely, higher than 1*630, and 

 lower than 1*740. The refraction of zoisite ranges from i'6g6 to 

 1702. 



No. g4 — 216. Serpentine after picrite from Puga valley, Ladakh ; collected 

 by the late Dr. Ferdinand Stoliczka ; Sp. G. 2825. 



This rock is composed of serpentine, olivine, augite, and felspar ; 

 the first named being the most and the felspar the least abundant 

 mineral. 



The serpentine contains eyes of olivine, and exhibits the usual 

 mesh-structure and other characteristics of serpentine derived from 

 that mineral. The infiltration -canals running through it are, as 

 usual in olivine-serpentine, lined with banks of magnetite thrown 

 down as a chemical deposit in the course of the decomposition of the 

 olivine and the formation of the serpentine. 



The augite is colourless in transmitted light and is probably 

 malacolite or an allied species. It rarely exhibits decided cleavage, 

 but when it does, it is a close, single cleavage resembling that of 

 diallage. It is traversed by occasional cands of serpentine; but as 

 usual in such cases, the pyroxene has not yielded as readily to 

 aqueous agents as the olivine. 



The felspar is much decomposed, but it shows the albite twinning 

 of plagioclase. Judging from the angles of extinction (the highest 

 obtained in suitable cases was 25°) and from the fact that it contains 

 infiltration-canals, it appears to belong to the labnidorite species. 



iVo. 94 — 2*5. Serpentine, from Hanli (Rupshu) ; collected by the late 

 Dr. Ferdinand Stoliczka ; Sp. G. 2-604. 



This is an ordinary serpentine rock. It exhibits the usual mesh- 

 structure, and is composed of the minerals serpentine, magnetite and 



( 17 ) 



