Sénarmontite
Sénarmontite is an extremely rare mineral and gem. Crystals are very scarce and usually small. Sénarmontite forms excellent octahedral crystals that can be transparent and colorless to gray. It is a very soft (2.0 – 2.5) but dense (5.2 – 5.3) mineral often with an adamantine luster.
The only source of gem quality crystals is the Djebel Haminate Mine, Ain Beida, Constantine Province, Algeria.
| Formula: | Sb2O3 |
| Antimony(III) Oxide | |
| Crystallography: | Isometric – Hexoctahedral |
| Crystal Habit: | Commonly as octahedra, to 3 cm, which may be modified by the cube or dodecahedron; in crusts, granular massive. |
| Twinning: | None |
| Cleavage: | [111] Poor/Indistinct in traces |
| Fracture: | Irregular/Uneven |
| Tenacity: | Very Brittle |
| Hardness (Mohs): | 2.0 – 2.5 |
| Density: | 5.2 – 5.3 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Color: | Colorless, White, Gray |
| Transparency: | Translucent to Transparent |
| Luster: | Adamantine, Sub-Adamantine, Resinous |
| Refractive Index: | 2.087 Isotropic |
| Birefringence: | 0.0 (Isotropic) |
| Pleochroism: | None |
| Anisotrophism: | Strong anomalous anisotropism, sectored or zoned. |
