92 The Sedimentary, Metamorphic, 



The strike of the schists is probably about N. 10° W., 

 and the veins are intrusive. 



I prepared examples of the two varieties of this schist, 

 one siliceous and the other pinite. The former is grey in 

 colour, with a tinge of olive-green. In the hand specimen 

 one can see that the quartzose foliations are separated by 

 narrow partings of basic materials. Under the microscope 

 I observed it to be a schistose compound of quartz, 

 felspars, two kinds of mica, pinite, and chlorite. The 

 felspars are in angular grains, and are all triclinic, 

 with low obscuration angles. t The measurements which I 



made in the zone OP — oo P go were between 1° 30' and 

 11° 30'. The micas are magnesia and alkali micas, 

 which in many cases are associated together. The 

 former is much chloritised, but where intact the dichroism 

 is not strong. The pinite occurs in irregularly-shaped masses. 

 The quartz grains are such as I have before described in 

 these schists, and make up by far the larger part of the rock. 



The second variety examined is a pinite schist with quartz 

 grains. 



The pinite forms foliations separated more or less by 

 irregular continuous partings of magnesia-mica with some 

 alkali-mica. The pinite has the same appearance under the 

 microscope which I have already described, but a few addi- 

 tional remarks may be made with advantage. In slices 

 parallel to the foliations it has aggregate polarisation, and in 

 places also a "meshed" structure, resembling that of serpentine. 

 No unaltered parts of any original mineral remain, but in 

 place there are what seem to be pseudomorphs after cordierite. 

 When examined by ordinary light, and with a power of about 

 55 linear, such individuals are seen to be made up principally 

 of minute bent and twisted flakes, which, as seen edgeways, 

 have the appearance of fibres. The larger ones react like an 

 alkali-mica. 



In a slice across the foliations the pinite had a much more 

 serpentinous appearance, the meshed structure being more 

 marked. 



The magnesia-mica is brown in tint, and not very 

 pleochroic. It is very much intergrown with alkali- mica, 

 not only by alternations, but also by the juxtaposition of 

 the two micas. The quartz is in isolated rounded grains, 

 almost in all cases in the micaceous foliations, and but rarely 

 in the pinite. 



