SOME CANADIAN MINERALS. 83 
The rock in both cases is a true diabase, although that examined by Thomson was 
supposed by him to be hornblendic. In each case, the microscope shows the presence of 
augite, a green chloritic mineral, titanic iron ore, and a more or less decomposed plagio- 
clase, the altered portions of which are probably identical with the so-called “ huronite.” 
III].— APATITE. 
Though much has been written with regard to Canadian apatite, little attention 
seems to have been paid to its crystalline form. In so far as the writer’s observation goes, 
the crystals of most common occurrence consist simply of a combination of the hexagonal 
prism and pyramid (GP. P.). A large proportion of the crystals from Renfrew County, 
seul 11 il 
ApPATIrE CRYSTAL FROM RENFREW, ONTARIO. 
however, exhibit the end-face in combination with the above forms, and resemble the 
well-known crystals from Snarum in Norway. More rarely, the Renfrew crystals have 
their vertical edges truncated by the prism of the second order, 2P2,* while in a few 
cases, which have recently come under the writer’s notice, a pyramid of the second order 
(2P2) is also present, the full combination in this case being, as shown in the accompanying 
drawing, coP. P. 0P. 2P2. coP2. 

* Crystals from Bob’s Lake, Bedford, Ontario, also show this form. 
