Vol. 56.] THE GEOLOGY OF GILGIT. 343 



I have noted the solvent action of the quartz on the micas 

 and felspars of the Hatu Pir Granite. This action, as might have been 

 expected, is even more noticeable in the variety under consideration. 

 For instance, in one of the specimens the felspar is deeply corroded 

 by the quartz. The latter mineral nibbled into the felspars and 

 formed bays all round their margins. It also penetrated into the 

 heart of crystals, forming gulfs and lakes, so to speak, and cut up 

 what were once large felspars into strips of fantastic shape. In 

 other examples the quartz has penetrated felspars in a way that 

 recalls the structure of perthite. That these strips are quartz and 

 not waterclear felspar, however, I have proved in many cases by 

 obtaining a well-defined cross in converging polarized light. 



The acid variety has suffered even more than the Hatu Pir Granite 

 itself from dynamical action. Most of it is strongly foliated, and two 

 of the specimens from Nanga Parbat arc very schistose. 



(4) The Askurdas Muscovite-Granite. 



This granite is composed of quartz, orthoclase, oligoclase, and 

 muscovite. 



Felspar predominates over quartz, and orthoclase over plagioclase 

 in three out of four cases. A little andesine is present in two slides. 

 The Askurdas rock differs from the Hatu Pir normal and acid 

 granites in the total absence of apatite, allanite, epidote, and sphene, 

 and the sparseness of magnetite and biotite. Some microciines and 

 granophyres are to be seen in one slide. 



The structure of the rock is granitic, but it bears evidence of 

 strain, and some of the quartz and felspar is broken up into 

 tessellated grains. In this rock also quartz appears as a corrosive 

 agent, eating into the felspar in veins and blebs, and cutting up 

 the orthoclase into strips and fragments, which it involves in its 

 flow. 



Two of the four slices contain pale pink garnets, and one a 

 little calcite. Some secondary silvery mica is occasionally present, 

 as well as original muscovite. 



The quartz contains strings of liquid cavities with moving 

 bubbles. 



The garnets are very prominent in three of the hand-specimens. 



(5) TheAplites. 



These occur as small veins in the crystalline limestones. The 

 felspars in the aplite are orthoclase, microcline, and plagioclase : 

 the last-named does not exhibit any twinning. A little magnetite 

 is present, and the samples are much stained with ferric oxide. 

 Much of the quartz is broken up into a mosaic, and in one slide 

 there is strong parallelism of structure. The larger quartzes either 

 form eyes, or have been drawn out into long sausage-shaped crystals. 



