470 Prof. T. G. Bouney and Miss C. A. Raisin. 



speckled, or somewhat fibrous, with indications of minute aggregate 

 polarisation, this being most conspicuous when it makes an angle 

 of 45 with the vibration planes of the crossed nicols. The fibrous 

 mineral very closely resembles the so-called sericite of some porphy- 

 roids. Here and there are grains of quartz, decomposed and some- 

 times broken felspar crystals, and some dark reddish, flaky patches. 

 The dark microscopic spots contain corroded grains of quartz, decom- 

 posed or partly corroded felspar crystals, and the same dark red 

 flaky minerals in a crypto- to micro-crystalline matrix. In one 

 rounded lump, at first sight very like a pebble, some grains of 

 crystalline calcite are enclosed. The smaller patches, though varying 

 in detail, present a general resemblance, and there can be little doubt 

 that they are fragments of a devitrified acid igneous rock. In the 

 absence of definite characters, it is difficult to speak positively as to 

 the nature of the matrix, but most probably it was once a volcanic 

 glass, which has since undergone micro-mineralogical change, mainly 

 in consequence of pressure.* 



Though the red patches occasionally look very like pebbles, it is 

 more probable that they are due to a flow brecciation. If we are 

 right in our inferences, these rocks of the Golden Throne indicate an 

 outpouring of acid lavas prior to the mountain making. Other 

 specimens from the same district are generally similar to the above- 

 described, but present varietal differences, and a small specimen of an 

 Indian red colour from debris on the Baltoro glacier is very probably 

 a tuff, though the amount of crushing makes it difficult to be sure. 



The crystalline schists include epidote-, Piedmontite-, and various 

 mica-schists. The first of these very probably occurs as a band in a 

 hornblende-schist, and a rock very similar to it may be found at 

 more than one locality on the Lizard peninsula, in Cornwall. The 

 second schist will be described more fully below. The third group 

 contains several varieties, one of which will receive a separate notice. 

 Of the rest, it may suffice to say that with one exception they are 

 ordinary types ; this, however, though a well known one, has suffi- 

 cient interest to warrant a slightly fuller description. The rock, 

 which comes from the Hnnza Valley, between Gulinet and Tashot,f 

 is a dark lead-coloured schist containing garnets. The latter, on 

 microscopic examination, are found to be a pale reddish colour, some- 

 times fairly regular in outer form, cracked, granular in structure, 

 and often containing a fair amount of dusky enclosures. These have 

 a somewhat dendritic grouping ; the angles which the tufts make 

 one with another are such as to suggest relations with the process 



* As has happened in many porphyroids (T. G. Eonncy, ' Proc. Geol. Assoc.,' 

 vol. 9, 1885, pp. 250258). 



f Many fragments of this rock were lying along the bottom and slopes of the 

 valley. Multitudes of garnets were found a little higher up the valley. W. M. C. 



