About the Properties of Epidote, Axinite, and Diopside

EPIDOTE.

Epidote usually occurs in a peculiar yellowish-green, called pistachio green, a color that is seldom found in other minerals. Besides this color, olive, brownish-green, greenish-black and black, red, yellow-gray, and grayish-white occur. The hardness of epidote is 6 to 7; specific gravity, 3.32 to 3.50; lustre, vitreous to pearly; refraction, double. The stone is transparent to opaque, is attacked by acids, and is slightly affected by the blow-pipe. It is composed of:

Silica 38

Alumina 22

Ferric oxide 15

Lime 23

Water 2

Epidote is found in Norway, Saxony, Siberia, Brazil, on the St. Gothard, in Switzerland, in the Tyrol, and in the Hartz.

AXINITE.

Axinite is a brittle mineral which has occasionally furnished some pretty gem stones.

The hardness of this stone is 6.5 to 7; specific gravity, 3 to 3.3; lustre, vitreous. It is transparent to translucent, is not attacked by acids, and melts readily before blow-pipe. It is composed of:

Silica 43

Lime 20

Alumina 16

Ferric oxide 10

Borontrioxide 5

Manganese dioxide 3

Magnesia 2

Potash 1

Axinite occurs in clove-brown, plumblue, and pearl-gray, and exhibits trichroism. The best specimens come from St. Christophe in Dauphiny, but it is also found at Santa Maria, and in Switzerland, Sweden, England, Chili, Saxony, the Hartz Mountains, and the United States.

Axinite is usually cut, like the opal, cabochon, but is rarely used as a gem stone.

DIOPSIDE.

Diopside is cut and sometimes sold in Turin and in Chamouny as a gem stone, but no great quantity of this mineral is used for ornamental purposes.

The hardness of diopside is 5 to 6; specific gravity, 2.9 to 3.5; lustre, vitreous to greasy. It is transparent to translucent, brittle, cannot be dissolved by acids, and melts before the blow-pipe. It is composed of:

Silica 54

Lime 24

Magnesia 18

Ferrous oxide 4