CRYSTALLINE SCHISTS OP THE MALYEEN HILLS. 529 



with the parallel structure, being filled with either iron-oxide or 

 mica. The quartz lies in wedges rather than folia. They are 

 approximately parallel, roughly lenticular in section, and rarely 

 continuous across the slide. Sometimes lines of quartz-grains curve 

 round the felspars. In one part of the field an angular bit of 

 quartz is immersed in a confused mass of quartz and felspar in 

 granules. The parallelism of the quartz seems at some points to be 

 determined by cracks, which are occupied by infiltrated products. 



The felspar has the brown cloudiness of the uncrushed granite. 

 It is very much cracked, and where crystals are defined they are 

 rather flattened, aud often tail out to a point on each side, so as to 

 resemble a human eye in shape. Some of the felspar, forming bands 

 of small crystalline grains between the quartz folia, is very dirty. 



Mica is very small in quantity. It occurs in some of the narrow 

 cracks in quartz, and in some of the felspar, and rarely it forms a 

 sort of sheath to the attenuated ends of the eye-shaped crystals. 



No. 283. Erom the same piece as the last, within a few inches 

 of it, but showing such clear lamination that it caught my eye 

 at a distance. Under the microscope it is much more like a gneiss. 

 The field is clearer, and there is much less cracking of the minerals. 

 The folia of quartz are longer, thinner, and more uniform in 

 thickness. In a few parts the quartz is traversed by longitudinal 

 cracks, but their mode of origin is less evident. Most of the felspar 

 is in regular folia of small crystalline grains, but there still remain 

 a few of the larger felspars with rounded and irregular outlines. 

 Some distinct folia of mica now make their appearance amongst 

 the felspar, but the quantity is still small. There has evidently 

 been much reconstruction of the minerals in this slide. 



No. 284. Part of the same block, but with the flaggy structure, 

 and showing in the field dark seams of mica. The quartz-folia are 

 still longer than in No. 283 and more regular in thickness. In 

 some spots a thin folium bends out of its course round a crystal of 

 felspar. The felspar is similar to the last. Seams of small granules 

 of this mineral also are seen to curve out of the straight line round 

 large crystals. The notable difference between this and all the 

 preceding slides is in the much greater proportion of mica. It 

 often occurs in regular folia between the quartz. Sometimes it forms 

 a complete sheath to an eye-shaped felspar-crystal. In one place a 

 felspar has been cracked obliquely across, and the crack is filled in 

 with mica. Thus each half of the crystal forms an almond-shaped 

 " eye," with its fringe of mica. There can be no question that this 

 mica, which is the same in all the set of slides, has been formed 

 out of the felspar. 



No. 285. Prom the flaggy schists to the north of the last. The 

 structure of the rock strongly suggests a similar origin. There is 

 more quartz, which here and there looks as if the lines separating 

 its folia had originally been cracks. Several cracks also cut across 

 the foliation, and these are filled in with mineral matter, which in 

 one spot is seen to be optically continuous with a regular folium. 

 At another point an elongated granule of quartz, forming part of 



