On Rocks and Minerals from the Karakoram Himalayas. 469 



small glittering crystals of bastite, brought from debris at foot of a 

 slope at the village of Mapnun on the Burzil Pass. The rock has 

 been evidently affected by pressure, and is practically identical with 

 a type of serpentine rather common in the Alps. 



Many varieties of diorite have been collected. Of these, some are 

 almost hornblendites (see below), others are normal diorites varying 

 from coarse to fine grained, others, again, are really hornblende- 

 schists. In some of the last it is likely that the foliation (as we 

 believe to be generally the case with the hornblende-schists of the 

 Lizard and of Sark)* is the result of fluxional movements anterior to 

 consolidation, while in others this structure is more probably due to 

 pressure, and to consequent mineral changes subsequent to the first 

 solidification of the rock. 



Granites are rather numerous. Some are of a normal type, mode- 

 rately coarse grained, the mica (variable in quantity) being generally 

 biotite. Certain of these are slightly gneissoid in structure. More 

 definitely foliated, almost certainly as a result of pressure, are some 

 rather micaceous (biotite) granites. Yet more distinctly gneissic 

 rocks occur, with a mineral banding as well as a foliation, in which 

 pressure modification is generally to be noted. One group of these has 

 a rather markedly different character ; they are fine grained gneisses, 

 modified by pressure (to which, however, the texture does not appear 

 to be due), not rich in quartz, consisting mainly of felspar (orthoclase 

 or microcline and plagioclase) and biotite, with a more or less defi- 

 nitely banded structure. They present a considerable resemblance to 

 certain rocks found in the district about Blair Athol (Scotland), 

 which Dr. H. Hicks, in consequence of their rather peculiar aspect, 

 has named the " pepper and salt " gneisses. We find also a coarse 

 granite, rather porphyritic in structure, and rendered gneissoid by 

 pressure, which contains large red impure garnets, up to about in. 

 in diameter. Similar garnets, but of smaller size, also occur in 

 several varieties of granite and gneiss ; one of these might almost be 

 called a kinzigite, others are granulites (leptynites). 



The compact acid igneous rocks are not numerous ; but a rather 

 remarkable series from the neighbourhood of the Golden Throne 

 calls for a little notice. Some come from the moraine proceeding 

 from the west foot of the mountain. These are compact, but show a 

 schistose structure with slightly micaceous or talcose aspect, indica- 

 tive of crashing. They are pai'ti -coloured ; a grey, varying from 

 slightly to markedly greenish, being streaked, spotted, and blotched 

 with a dull Indian red, small white specks showing in some of the 

 patches. The texture of the lighter part under the microscope is 



* T. G. Bonney and General C. A. McMahon, ' Quart. Jl. Geol. Soc.,' vol. 47 

 (1891), p. 497; E. Hil! and T. G. Bonney, 'Quart. Jl. Geol. Soc.,' vol. 48 (1892) 

 p. 145. 



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