Pyroxmangite
Pyroxmangite is a very rare gemstone that is difficult to cut due to its perfect cleavage. The chemical formula of Pyroxmangite is Mn,Fe2+SiO3 (Manganese Iron Silicate) and its molecular weight is 131.20 gm. The mineral is usually found as small grains that are seldom large enough or clean enough to facet. Pyroxmangite has a specific gravity of 3.61 – 3.80 (g/cm3) and the refractive index of 1.728 – 1758 Biaxial ( + ). Moh’s Hardness is 5.5 – 6.0. Pyroxmangite is similar in appearance and properties to Rhodonite and Bustamite.
There are very few locations for gem quality crystals. Nice crystals have been found at Broken Hill, New South Wales, Australia and Minas Gerais, Southeast Region, Brazil.
| Category: | Inosilicate |
| Chemical Formula: | Mn,Fe2+SiO3 |
| Manganese Iron Silicate | |
| Molecular Weight: | 131.20 gm |
| Composition: | Manganese | 33.50 % | Mn | 43.25 % | MnO |
| Iron | 8.51 % | Fe | 10.95 % | FeO | |
| Silicon | 21.41 % | Si | 45.79 % | SiO2 | |
| Oxygen | 36.58 % | O | |||
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Triclinic – Pinacoidal |
| Crystal Habit: | Crystals typically tabular, to 10 cm; porphyroblastic, granular. |
| Twinning: | Lamellar on {010}, simple on {001}, uncommon. |
| Cleavage: | {110} Perfect, {110} Perfect |
| Fracture: | Irregular/Uneven |
| Tenacity: | Brittle |
| Moh’s Hardness: | 5.5 – 6.0 |
| Density: | 3.61 – 3.80 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Other: | Magnetic after heating. |
| Color: | Pink, Rose Pink, Purplish Pink, Red; commonly covered with Brown or Black oxidation products |
| Transparency: | Translucent to Transparent |
| Luster: | Vitreous to Pearly |
| Refractive Index: | 1.728 – 1758 Biaxial ( + ) |
| Birefringence: | 0.0160 – 0.0180 |
| Dispersion: | Moderate; r > v |
| Pleochroism: | None |
