Euclase is very brittle, and therefore is rarely used as an ornamental stone.
This mineral has the hardness of 7.5; specific gravity, 3.1; lustre, vitreous to pearly; it is transparent to semi-transparent, doubly refractive, is not acted upon by acids, fuses under the blow-pipe to a white enamel, and is composed of:
| Silica | 41.2 |
| Alumina | 35.2 |
| Glucina | 17.4 |
| Water | 6.2 |
Euclase occurs in Brazil, in the neighborhood of Villa Rica, and also in the Urals, in colorless, pale green, blue, pale yellow, and white colors.
Sphene.
Sphene or titanite is also a brittle mineral, 5 to 5.5 in hardness; specific gravity, 3.4 to 3.56; transparent, doubly refractive; lustre, adamantine to resinous; colors, brown, gray, yellow, green, black, and colorless; and composition:
| Silica | 31 |
| Titanium oxide | 41 |
| Lime | 27 |
| Ferrous oxide | 1 |
When transparent in colorless, greenish, or yellow colors, this mineral presents an appearance like the fire opal.
Sphene is found in Switzerland, the Urals, Tyrol, Finland, Wales, Ireland, Germany, Canada, and the United States.