Viridine
Viridine is the Manganese bearing, green variety of Andalusite. The Manganese gives Viridine its rich, grass green color. It is a rare gem and usually very small. Sources of Viridine are Belgium, Brazil, Germany and Sweden but most gem quality crystals come from Bahia, Northeast Region, Brazil.
| Crystallography: | Orthorhombic – Dipyramidal |
| Crystal Habit: | As euhedral crystals or columnar aggregates having nearly square cross sections, commonly elongated, to 20 cm. Also fibrous, compact, massive. |
| Twinning: | On [101], rare. |
| Cleavage: | [110] Good, [100] Poor |
| Fracture: | Uneven to Sub-Conchoidal |
| Tenacity: | Brittle |
| Hardness (Mohs): | 6.5 – 7.5 |
| Density: | 3.13 – 3.17 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Color: | Light to dark Green |
| Transparency: | Transparent to nearly Opaque |
| Luster: | Vitreous |
| Refractive Index: | 1.66 – 1.69 Biaxial ( + ) or ( – ) |
| Birefringence: | 0.0290 |
| Dispersion: | Strong; r < v |
| Pleochroism: | Weak |
