MINERALS AND GEOLOGY OF CANADA. 519 
the leading varieties of quartz. Thus we have, Rock Crystal (including 
the so-called “ Quebec diamonds,” &c.); Smoky Quartz, a brown 
variety of rock erystal ; Amethyst, a purple or violet-coloured quartz, 
in which the edges of the crystals are usually more deeply coloured 
than the other parts; Cairngorm, a yellow transparent quartz ; Rose 
Quartz ; Milk Quartz, a white translucent variety ; Calcedony and 
Cornelian, grey, white, bluish, yellow, and red, uncrystallized 
translucent varieties of quartz; Cad’s-eye, an opalescent or chatoy- 
ant caleedony; Chrysoprase, a light green translucent variety ; 
Heliotrope, a dark green variety, sometimes with red spots and 
then called Bloodstone; Plasma and Frase, other green varieties, 
the latter often mixed with actynolite; Ayate, Onyx, Sardonyz, 
‘&e., unerystallized varieties of various banded colours; Jasper, 
coarse, opaque, red, brown, and other coloured specimens, often 
striped, and with dull lustre on the fractured surface; Fliné and 
Hornstone, &c. Crystallized quartz occurs in various parts of 
Canada, more especially where Laurentian rocks prevail, and in the 
altered rocks of the eastern townships. Amethyst is found abun- 
dantly on Spar Island, where it forms a broad vein with calc-spar 
holding native silver, and at Thunder Bay and other spots on Lake 
Superior. Agates, also, in great variety, occur in the trap rocks and 
in the shingle beaches of that region (Michipicoten Isle, St. Ignace, 
Thunder Bay, &c.) A jasper-conglomerate, evidently an altered 
sedimentary rock, occurs on the north shore of Lake Huron. Agates 
and red and green jaspers occur also in Gaspé. ed jasper passing 
into jaspery iron ore, likewise near Sherbrooke ; and, with veins of 
calcedony, on the river Ouelle (Kamouraska Co.) C. E. Silica 
often constitutes the fossilizing substance of organic remains, as in 
the Devonian corals of western Canada; and it is frequently found 
in crystal-groups in the inside of many fossil shells. Finally, it may 
be observed, quartz forms one of the essential components of 
granite, gneiss, and many other crystalline rocks. Sandstones 
also consist essentially of quartz grains cemented together, or 
consolidated by pressure; whilst in beds of sand and gravel we 
have the same substance in loose grains and pebbles, as explained 
more fully in Part III. 
Zircon.—Red, brown, or grey, with resino-vitreous aspect. Chiefly 
in small crystals: (square-based prism-pyramids), fig. 38. H.75; sp. 
gr. 4°0-4°7. Quite infusible. One hundred parts consist of: silica 
