EXPOSITION OF THE MINERALS AND GEOLOGY OF CANADA. 51°} 
A POPULAR EXPOSITION OF THE MINERALS AND 
GEOLOGY OF CANADA. 
BY E. J. CHAPMAN, 
PROFESSOR OF MINERALOGY AND GEOLOGY IN UNIVERSITY COLLEGE, TORONTO. 
(Continued from page 182.) 
Our last paper of this series, inserted in the present volume of 
the Journal, pages 168-182, contained a tabular distribution, with 
brief descriptions, of all Canadian minerals of metallic aspect: these 
falling under sub-divisions 4 and B of the classification given on 
page 170. The present paper includes the minerals belonging to 
sub-division C; and in the next number, those of the fourth sub-division 
will be given, completing this portion of our subject. 
C. Aspect, non metallic (stony, glassy, etc.) Hardness sufficient to 
scratch glass 
C.1—Infusible. Very hard, not yielding to the knife. 
[Quartz is the only mineral of common occurrence, belonging to the present 
section. In colour, degree of transparency, and general appearance, this substance 
varies exceedingly ; but its specific gravity is always under 2:9, whilst the other 
minerals (of Canadian occurrence) included in the section, exceed 3-0 in density. 
Feldspar is sometimes confounded by beginners with quartz; but the former in 
thin splinters, is more or less readily fusible. The two minerals may be distinguish- 
ed also, at once, by the following characters: Quartz breaks with an uneven or 
eonchoidal fracture, and never exbibits smooth cleavage planes. Feldspar, on the 
other hand, possesses a strongly-marked lamellar structure, and breaks easily in 
certain directions, so as to present a smooth, polished, and somewhat pearly 
fracture-plane. | 
Corundum.—Red, blue, brown, greenish, black, &c. In small 
granular masses and hexagonal erystals. HH. 9°0, and hence much 
above that of quartz; sp. gr. 3°9-4°1. Quite infusible. Corundum: 
consists, normally, of pure alumina. The transparent red varieties. 
constitute the Huby of commerce, and the blue varieties the Sapphire.. 
The coarser dull-coloured varieties are called Adamantine spar; and 
tke opaque, black and dark grey varieties (often mixed with magnetic: 
iron ore) form Emery, a substance used largely, from its great hard-. 
ness, as a polishing material. Some of the finer kinds of corundum 
exhibit when cut, a beautiful opalescent six-rayed star. These are- 
