Rhodonite
Rhodonite is mostly found as an abundant opaque mineral and popular for cabochons and carvings. It is very rare as a faceted gem due to the scarcity of transparent material. It is also considered one of the most difficult of all gems to facet because of its easy, perfect cleavage. It is closely related to Pyroxmangite and Bustamite.
Most Rhodonite sources only produce massive, opaque speciments. A few locations for gemmy crystals include Broken Hill, Yancowinna County, New South Wales, Australia; Minas Gerais, Southeast Region, Brazil; and Huallanca, Bolognesi Province, Ancash Department, Peru.
| Category: | Inosilicate |
| Formula: | (Mn2+,Fe2+,Mg,Ca)SiO3 |
| Crystallography: | Triclinic – Pinacoidal |
| Crystal Habit: | Crystals rough, with rounded edges, typically tabular and elongated, to 20 cm; commonly massive, cleavable to compact. |
| Twinning: | Lamellar, with [010] as composition plane. |
| Cleavage: | [110] Perfect, [110] Perfect |
| Fracture: | Conchoidal to Irregular/Uneven |
| Tenacity: | Brittle |
| Hardness (Mohs): | 5.5 – 6.5 |
| Density: | 3.57 – 3.76 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Color: | Pink, Rose Red, Brownish Red, Yellow, Black; exterior commonly black from manganese oxides |
| Transparency: | Translucent to Transparent |
| Luster: | Vitreous, somewhat Pearly on cleavages |
| Refractive Index: | 1.711 – 1.751 Biaxial ( + ) |
| Birefringence: | 0.0130 |
| Dispersion: | None; r < v |
| Pleochroism: | Weak; X = yellowish red, Y = pinkish red, Z = pale yellowish red |
