Granites from British Columbia, etc. 355 



some other metamorphic agency, but which did not com- 

 plete their growth. 



3. Minerals which have grown in the rock after its 

 solidification, but without re-crystallization of the other 

 constituents. 



The first hypothesis does not seem to be tenable in the 

 present case, for not only is epidote a mineral which occurs 

 but very rarely in granites, except as a decomposition 

 product, but a careful examination under the microscope 

 would seem to show that, as above mentioned, the apparent 

 corrosion of the crystals, whether epidote, muscovite or 

 calcite, is quite different in character from that produced 

 by the corrosion and partial resolution of a caustic magma. 

 If the muscovite were so corroded, the biotite should also 

 have been attacked with the removal of the muscovite 

 molecule at least. 



Further, if a crystal of muscovite were eaten away until 

 the merest skeleton alone remained, or until the crystal had 

 actually been separated into several pieces, it would be im- 

 possible for the entire skeleton and even the several dis- 

 connected portions to preserve exactly the same orientation 

 had there been the slightest motion in the molten magma, 

 and we cannot but suppose that there would be a certain 

 amount of motion when such extensive resolution was 

 taking place. 



Moreover, as above mentioned, there is reason to'believe 

 from their similarity in mode of occurrence and close associa- 

 tion, that the epidote, muscovite and calcite, have had a 

 similar origin, but we would hardly expect calcite as an 

 original mineral in so acid a rock, much less crystallized 

 in large individuals in actual contact with quartz. 



Neither does there seem to be reason to believe, after a 

 careful study of the thin sections of the rock, that anything 

 like an entire crystallization of the granite has taken place 

 as supposed in the second hypothesis. Were it not for the 

 epidote, muscovite and calcite, the rocks would be considered 

 normal granites probably somewhat crushed. Their 

 character is that of eruptive rocks, not of crystalline schists. 



