On Rocks and Minerals from the Karakoram Himalayas. 479 



placed by lime. It is roughly intermediate between a lime-margarite 

 and a meroxene described by Dr. Grubenmann.* 



(3.) Mineral or Vein Specimens. 



A considerable number of the specimens brought by Mr. Conway 

 are vein-stones, or representative of minerals rather than of rocks. 

 Quartz, of course, is common ; calcite, dolomite, and chalybite not 

 unfrequent. Besides these are found the following : Anhydrite, 

 actinolite, idocrase, noble serpentine, copiapite (probably from decom- 

 position of pyrite), and almandine. There are numerous examples of 

 common garnet, many of epidote and of tourmaline ; also of pyrite, 

 with chalcopyrite and other copper ores, usually in small amount. 

 We have looked carefully for gold in the pyritiferous quartzose veins 

 and other specimens, but have not detected any traces. One speci- 

 men alone seems to call for special notice a pseudojade and 

 this perhaps is, more strictly speaking, a rock rather than a mineral, 

 but we place it here since it was a fragment on a moraine (left half 

 of the Baltoro Glacier), and nothing is known as to its origin. Its 

 form is angular, being partly limited by joints ; it is of a variably 

 greenish colour, irregularly mottled by a pale yellowish tint. The 

 hardness is about 6'5, the sp. gr. 3'26, and the general appearance 

 suggests a jade, but it differs in microscopic character from the few 

 specimens of that rock which we have examined. f A slice exhibits, 

 in ordinary transmitted light, a ground mass of a very pale yellowish 

 colour, containing irregular, dusty looking patches and lines, variable 

 in their distribution. The parts freer from these enclosures are 

 almost inert on polarised light, but contain at places a fibrous flaky 

 mineral, extinguishing straight, and very faintly polarising with dull, 

 olive-brown colours. This we find to correspond generally with the 

 greener parts of the specimen. The more dusty intervals (those 

 corresponding with the paler parts), exhibit, with crossed nicols, dis- 

 tinctly marked aggregates of very minute granules, and also a fibrous 

 prismatic mineral, rather more brightly polarising, extinguishing at 

 a fairly high angle, and having a somewhat matted arrangement : not 

 improbably a pyroxene. There are some rather clustered granules 

 and grains of a translucent brown mineral, seemingly isotropic, 

 possibly a variety of garnet. 



We have to thank Mr. P. Williams, of University College, for the 

 following analysis, made in Professor Ramsay's laboratory. 



* Quoted in ' Quart. Jl. Geol. Soc.,' vol. 46 (1890), p. 227. 



f General C. A. McMahon has been good enough to examine the slide and to give 

 us the benefit of his experience of Indian rocks, determining at the same time the 

 specific gravity of the specimen and making a qualitative analysis. 



