Wild. — Geology of the Bluff. 



333 



resorted to : Having made a sufficient number of sections to ascertain 

 the thickness of the covering of uralite, crystals were ground down on 

 all faces to remove this portion. The remainder provided material for 



an analysis of the core of augite. 

 cleaved, and the analysis of these 

 position of the uralite. 



From other crystals thin flakes were 

 was taken as representing the com- 



Specific gravity 



3-00 



2-6315 



3-181 



3-003 



A. Augite. 



From dyke of amphibolite. Bluff. 



B. Uralite. Forming exterior of A. 



C. Central portion of pyroxene crystal, Templeton, Quebec. (Anal., 

 Harrington, Geol. Canada, p. 21, 1879.) 



D. Amphibole forming exterior of C. (Anal., Harrington, Geol. 

 Canada, p. 21, 1879.) 



These analyses emphasize the change in the relative amounts of 

 magnesia and calcium. There is also in the case of the uralite a rise in 

 the percentage of alumina and iron-oxides corresponding to a fall in the 

 total percentage of magnesia and calcium. This is what we might expect 

 in the case of a mineral derived from another mineral by hydro-chemical 

 processes. The process of uralitization is commonly reported to be 

 accompanied by the separation of calcite and by the formation of 

 epidote.* In the case of the Green Point minerals the augite un- 

 doubtedly loses calcium, but neither calcite nor epidote are seen as 

 decomposition-products. 



Both sets of analyses emphasize the fact that the change of augite to 

 uralite is not strictly a case of paramorphism, though usually so desig- 

 nated. 



The causes that led to the production of uralite are discussed later 

 under the heading " The Origin of the Amphibolite." 



III. Relationship between the various Rock Types. 



It has already been stated that there is a close relationship existing 

 between the porphyry and the hornblende-schist series. The relationship 

 between the amphibolite and the hornblende schists also requires explana- 

 tion, and it must also be shown what part the intrusion of the norite 



* See, e.g., "Microscopical Physiography of the Rock-making Minerals," Rosen - 

 busch-Iddings, 4th ed. (1900), p. 271. 



