112 The Sedimentary, Metamorphic, 



schists, for instance in Hornfels, the clastic origin of the 

 quartz grains is always more or less perfectly recognisable. 

 But in the Ensay schists this is not the case. They are 

 eminently schistose, ancl ; broadly speaking, the quartz 

 and the mica form separate foliations. Frequently the 

 quartz is in crystalline grains, whose form is rudely rect- 

 angular. In places the sections of these grains merely touch 

 each other, while in others they overlap in the direction of 

 the foliation. In other cases the foliation is continuous or 

 even branching, the quartz being traversed by cross-flaws. 

 Such observations point to the grains being flattened 

 parallel to the foliated structure, and to be probably, in some 

 cases at least, discoidal in form. In some slices I have found 

 all the quartz to be evidently of the same period of forma- 

 tion, as, for instance, where inclusions or fluid cavities are of 

 the same character throughout the thin slice. I note such 

 an instance wherein numerous fine, colourless, hair-like 

 microliths lie in the quartz veins throughout the slice, and 

 have all of them a uniform direction. In a few cases I 

 have been able to distinguish two generations of quartz, and 

 in others I have observed small rounded granules of quartz 

 included in the larger grains of the foliations. 



I have thus been led to the conclusion that during the 

 metamorphism of these once sediments the original quartz 

 grains have been taken into solution, and then finally 

 redeposited between the micaceous foliations. 



It seems to me that the silicification of these rocks could 

 have scarcely been effected by extraneous solutions permeat- 

 ing them as a whole, for in such a case one should, I think, 

 expect to find general and similar effects throughout. Such 

 has not been the case in this instance ; but, on the contrary, 

 one can observe that there are still two main varieties of 

 these schists corresponding to the arenaceous and argillaceous 

 sediments, and therefore the conclusion may be perhaps 

 justified that the silica, if taken into solution during the 

 metamorphic process, was, as they ceased, again redeposited 

 mainly in the sets of beds from which it had been derived. 

 If this view proves to be maintainable, it will have a strong 

 bearing upon other questions as to metamorphism which 

 await solution in the Omeo district as well as elsewhere.' 



The fine-grained mica schists show somewhat similar 

 features, but as they are much more micaceous than quartz- 

 ose, the peculiar appearances which I have just noted are 

 not so apparent. 



