266 T. S. Hunt on Lithology. 
diallagic diabase and diallagic ophiolite on the other. 
hese greenstones, which contain a chloritic mineral, and are 
metamorphism furnish evidences that similar compounds have re 
sulted from the action of heat upon mechanical! mixtures in sed- 
imentary deposits, (ibid. p. 581). A further consideration of this 
subject, and of the two-fold origin of many siliceous minerals 8 
reserved for another place. 
[To be continued. ] 
