Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC-BY-SA-3.0], via Wikimedia Commons
Senarmontite is a rare mineral, restricted in occurrence to the presence of antimony sulfide ores. It is much too soft to wear, and the colors are usually nondescript. However, a faceted senarmontite in any size would be a great rarity.
| Data | Value |
|---|---|
| Name | Senarmontite |
| Stone Sizes | There are reports of very tiny gems having been cut from transparent crystal fragments. Stones up to 1-2 carats seem possible. |
| Formula | Sb2O3. |
| Colors | Colorless to grayish white. |
| Fracture | Uneven |
| Hardness | 2-2.5 |
| Cleavage | Traces |
| Crystallography | Isometric. Crystals octahedral, up to 3 cm on edge; massive. |
| Refractive Index | 2.087 |
| Birefringence | None |
| Luminescence | None. |
| Luminescence Present | No |
| Absorption Spectrum | Not diagnostic. |
| Pleochroism | None. |
| Optics | Isotropic; N = 2.087. |
| Luster | Resinous. |
| Specific Gravity | 5.5. |
| Transparency | Transparent to translucent. |
SENARMONTITE Isomorphous with Valentinite.
Optics: Isotropic; N= 2.087.
Occurrence: A secondary mineral formed by the alteration of stibnite (Sb2S3)
Inyo County, California; South Dakota.
Quebec; Canada; Algeria; France; Germany; Sardinia; Italy.
Comments: Senarmontite is a rare mineral, restricted in occurrence to the presence of antimony sulfide ores. It is much too soft to wear, and the colors are usually nondescript. However, a faceted senarmontite in any size would be a great rarity.
Name: After Henri de Senarmont, professor of mineralogy at the School of Mines in Paris, who first described the species.
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