82 DISCOVERY REPORTS 



A few of the rocks, which must originally have been rich in calcareous and argillaceous matter, 

 contain abundant calcite and epidote. The latter mineral is no doubt produced by the well-known 

 reaction between calcareous and argillaceous matter during metamorphism. Quartz-calcite-epidote- 

 schists are thus formed. As the degree of metamorphism increases, epidote becomes the dominant 

 mineral with the dwindling or disappearance of calcite and sericite. The final product of this change 

 is a quartzose epidosite. All of these rocks are intersected by a profusion of secondary quartz veins. 



A rock which may belong to the above series is a saccharoidal metamorphic quartzite which carries 

 scattered and irregularly bounded patches of coarse sericitic material. This may perhaps be interpreted 

 as representing one of the thicker beds of sandstone that may have contained clay galls. 





Fig. II. Section of phyllite, showing folding. 



Another specimen shows many points of resemblance to the above-described series, especially in 

 the abundance of argillaceous material and the presence of calcite, epidote and sericite. It differs, 

 however, in that some of the folia are rich in large, angular fragments of alkali-feldspars, including 

 orthoclase and albite, which are still comparatively fresh. This may perhaps be best interpreted as 

 a sheared rhyolitic tuff, intermingled with normal sedimentary material. 



The remaining three stones of the metamorphic group are quartz-epidote-amphibole-schists which 

 have probably been derived from basic igneous rocks or their tuffs. One is a quartz-albite-tremolite- 

 epidote-schist ; the other two are calcite-quartz-glaucophane-epidote-schists. 



The first is a fine-grained, apparently bedded rock with a schistosity coinciding with the bedding 

 planes. It consists mainly of a mixture of minute grains of epidote with microlites of albite, and 

 prisms of colourless to pale green tremolite which have a tendency to lie athwart the planes of 

 schistosity. This material carries large and small folia consisting of quartz and albite, both enclosing 

 innumerable needles and thin plates of tremolite. The albite often forms large, simply twinned, 

 blasto-porphyritic crystals developed in a mosaic of quartz and small albites. The largest and coarsest 

 of these folia has a distinct resemblance to an aplite vein. This rock is somewhat difficult to interpret, 



