Veszelyite
Veszelyite is a very rare and beautiful copper and zinc phosphate mineral with a Mohs hardness of 3.5 to 4. It is an extremely rare gem and gems are very small since crystals are very small, usually, less than 10 mm and its crystal habit is Prismatic crystals, flattened, elongated, to 5 cm, also typically pseudo-octahedral; may be in granular aggregates.Its Optical character is biaxially positive and with the refractive index of 1.618 – 1.695. Mineral specimens are very attractive and very highly sought after by collectors. There are only a handful of localities for finding Veszelyite crystals. One of the best known is the Black Pine mine, near Philipsburg, Granite County, Montana, USA.
| Formula: | (Cu, Zn)2Zn(PO4)2 · 2H2O |
| Crystallography: | Monoclinic – Prismatic |
| Crystal Habit: | Prismatic crystals, flattened, elongated, to 5 cm, also typically pseudo-octahedral; may be in granular aggregates. |
| Twinning: | None |
| Cleavage: | [001] Distinct/Good, [110] Distinct/Good |
| Fracture: | n/a |
| Tenacity: | Brittle |
| Hardness (Mohs): | 3.5 – 4.0 |
| Density: | 3.40 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Other: | Soluble in acids. |
| Color: | Blue, dark Blue, Greenish Blue, Green |
| Transparency: | Translucent |
| Luster: | Vitreous |
| Refractive Index: | 1.618 – 1.695 Biaxial ( + ) |
| Birefringence: | 0.0400 – 0.0550 |
| Dispersion: | Weak to Strong; r < v |
| Pleochroism: | Weak; Z = Blue, X = Greenish blue |
