Notes on some Canadian Minerals. 475 



bination a = co P, b=P, c = 2 P2, the 2 P 2 faces being re- 

 markably well developed. (See Fig. 4.) 



Fig. 4. Quartz Crystal — Lac aux lies, Portneuf Co., P. Q. 



Mr. John Stewart, of Ottawa, has also presented me with 

 some interesting crystals of smoky quartz, from lot 44, 

 range 6, Bouchette township, Ottawa Co., Quebec. 



In these both prismatic and pyramidal faces are concave, 

 giving the crystal the peculiar appearance shown in Plate 

 II, which is reproduced from a drawing kindty made for me 

 by Mr. L, M. Lambe, the artist of the Survey. 



When a straight edge is laid across one of the prism faces 

 (I- in. wide), the deflection of the face from its normal posi- 

 tion, at a point half way across it, is seen to be about „ J lT of 

 an inch, the curvature being quite symmetrical. 



Similar crystals have been found in Orange County, New 

 York State. 



8. Spinel. 



Beautiful, brilliant, jet-black octahedrons of spinel were 

 lately found by Mr, John Stewart, in Aylwin township, 

 Ottawa county, Quebec, imbedded in a crystalline limestone. 



Perfect crystals in my possession measure § in, in dia- 

 meter, and some of them exhibit the combination of octahe- 

 dron and dodecahedron (o,oo o). 



A complete alteration of the mineral to some species of 

 mica has been observed in a few instances, 



9. Anhydrite and Gypsum. 



Mr. H. Lundbohm of the Geological Survey of Sweden, 

 who has recently been in Canada studying the mode of 

 occurrence of our apatite, placed in my hands for determ 



