Piedmont; in the Urals at Kossulina and Kolivan; near Bellary, in India.
It is distinguished from the Aventurine varieties of Felspar by its greater hardness.
12.
Varieties containing impurities are not of much importance in the
present relation, though a few used to be cut at the beginning of the
eighteenth century. The only kinds we need consider are: (1) Quartz,
containing Gold in the form of filaments, or scattered particles; in
America a considerable amount is cut for use as a fancy stone; but
elsewhere it is not often used, except by those who have had to do with
gold-mining. Material suitable for this purpose is found in Australia,
South Africa, and particularly in the Western States of America.
Similar inclusions of Silver are very rare. (2) Quartz containing
Haematite. This is known also as Sinople, Hyacinth of Compostella, and
Eisenkiesel. It is Quartz richly impregnated with the red oxide of
iron, Haematite, from which it derives its blood-red colour. It has
been used to imitate the variety of Zircon called Hyacinth, but is
distinguished from it by its inferior specific gravity. It is found in
beds of Gypsum at Compostella, in the north of Spain; also in Saxony,
Bohemia, and Hungary. The iron mines of West Cumberland afford some
very beautiful specimens, the colour in them possibly being due to
Turgite, and not to Haematite. The Compostella specimens usually occur
in short prisms, with a termination at each end.
13.
Quartz containing Liquids in Cavities. These forms, though of
considerable scientific interest, are rarely used now for ornamental
purposes, Some are cut in the United States as curiosities.
