LADAKH, NORTH-WESTERN HIMALAYA. 323 



The groundmass is composed of allo-triomorphic hornblende, 

 felspar prisms, and iron ores, namely, magnetite, ilmenite, pyrite and 

 limonite. 



The hornblende is pleochroic in shades of green and greenish- 

 yellow. It rarely exhibits any cleavage; and it is not at all fresh. 

 It polarizes sometimes in colours of Newton's first order, but a change 

 into chlorite had evidently begun, and had made progress in some 

 individuals. It, or the augite from which it was derived, was 

 evidently one of the last minerals to crystallise out of the cooling 

 magma, for it is micro-poikilitic and generally encloses several small 

 felspars wholly, or partially, within its crystals. Occasionally the 

 amphibole exhibits a tendency to become idiomorphic, but never 

 shows decided crystallographic outlines. 



The second generation of felspars vary very much in size, but 

 one that may be considered a fair average specimen measured 0*035 

 millimetres long by 0*0063 thick. The small felspars alluded to as 

 the second generation, are all either in binary or multiple twins. 

 The extinctions in those intermediate between the microliths and 

 large porphyritic felspars range from \6\ to 20J degrees ; and the 

 microliths from o° up to 22^°. Those extinguishing from o° to 6° 

 are probably oligoclase and the others acid labradorite with some 

 andesine or albite. 



None of the above three specimens were found in situ, but came" 

 from blocks in recent deposits. I described 1 a porphyritic volcanic 

 rock under the name of basalt-porphyry from the ridge above 

 Bhandal, in the Chamba territory on the borders of the Kashmir 

 State, which, macroscopically considered, very much resembles the 

 rocks under consideration. The basalt- porphyry exhibits por- 

 phyritic plagioclase felspars starred about in a dark-grey compact 

 matrix, which under the microscope is seen to be a matted mass of 

 felspar microliths in a finely granular base or groundmass. The 

 specific gravity of the Bhandal rock averaged 2*89 ; that of 



1 Rec. Geol. Surv. Ind., Vol. XVIII, p. 96. 



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