Sursassite
Sursassite is a rare manganese silicate mineral found at only a few localities around the world. Crystals are found as red-brown to copper-red fibers or botryoidal masses in veinlets. Sursassite has strong dispersion and pleochroism. Material from the Molinello manganese mine, near Chiavari, Val Graveglia, Liguria, Italy is rarely available as cabochons.
Sursassite is found in just a few locations around the world. From the Val d’Err, Oberhalbstein, GraubÄunden, Switzerland. In the Plymouth deposit, near Woodstock, New Brunswick, Canada. From the Palos Verdes Hills, Los Angeles County, California, USA. In the Molinello manganese mine, near Chiavari, Val Graveglia, Liguria, Italy. On Andros Island, Cyclades Islands, Greece.
| Chemical Formula: | Mn2+2Al3(SiO4)(Si2O7)(OH)3 |
| Manganese Aluminum Silicate Hydroxide | |
| Molecular Weight: | 502.09 gm |
| Composition: | Manganese | 21.88 % | Mn | 28.26 % | MnO |
| Aluminum | 16.12 % | Al | 30.46 % | Al2O3 | |
| Silicon | 16.78 % | Si | 35.90 % | SiO2 | |
| Hydrogen | 0.60 % | H | 5.38 % | H2O | |
| Oxygen | 44.61 % | O | |||
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Monoclinic – Prismatic |
| Crystal Habit: | As fibers, up to 2.5 cm, in veinlets and as radiated botryoidal masses. |
| Twinning: | None |
| Cleavage: | Distinct on {101} |
| Fracture: | Irregular/Uneven |
| Tenacity: | Brittle |
| Moh’s Hardness: | n/a |
| Density: | 3.256 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
Color: |
Red-Brown to Copper-Red |
| Transparency: | Translucent |
| Luster: | Silky, Dull |
| Refractive Index: | 1.736 – 1.766 Biaxial ( – ) |
| Birefringence: | 0.030 |
| Dispersion: | Strong; r > v |
| Pleochroism: | Strong; X = Z = colorless to pale yellow; Y = deep golden brown |
