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 |
This mineral is grayish-white to pearl-gray, and greenish-white to greenish-gray. The best green transparent specimens are from the Mussa Alp and Zillerthal, but it is also found in the Urals and the United States.