﻿vol. 6 1.] microscopic structure of serpentine. 715 



Discussion. 



The President referred to the interest that the Fellows must 

 feel in having a paper laid before them, in which, besides much 

 original information, there was a summary of the history of the 

 progress made in a group of rocks upon which one of the Authors 

 had thrown light thirty years ago. 



Dr. Teall remarked that the President had, to some extent, 

 anticipated what he was about to say on the importance of the 

 communication which had just been laid before the meeting. He 

 feared that he could not throw much additional light on the subject. 

 The main point appeared to be that, in addition to the serpentines 

 derived from peridotites, another important group existed, wherein 

 the structure was not the same, that was, the antigorite-serpentine 

 group. This was of more widespread occurrence than had pre- 

 viously been supposed, and was largely composed of altered augitic 

 rocks. His own experience, so far as it went, confirmed the 

 Authors' conclusions. He would be glad to learn the Authors' 

 views as to the origin of such augitic rocks as those from Canada : 

 was it possible that they represented altered siliceous dolomites or 

 rocks of a similar type ? 



Prof. Bonne y replied that he had meant to say that antigorite 

 might come from olivine or enstatite (there was enstatite in the 

 original Val-Antigorio rock), but that it came most readily from 

 augite. The origin of the augitic rocks of Canada was too long a 

 subject for the present occasion, but he did not believe that they 

 had been formed in the way suggested by Dr. Teall. 



Q.J.G.S. No. 244. 3e 



