Smithsonite
Smithsonite is a rare member of the Calcite mineral group that includes Calcite, Cobaltocalcite, Gaspéite, Magnesite,Rhodochrosite, and Siderite. It is available in several colors that are influenced by the addition of various other minerals. Pink colors are due to the addition of cobalt or manganese, yellows from cadmium, blues and greens from copper. It is also rarely found as colorless. The blue-green Smithsonite from the Kelly Mine in New Mexico, USA has been in high demand for many years. The combination of dispersion almost as high as Diamond and the beautiful, pearly to silky luster and unusual colors makes clean, faceted Smithsonite a magnificent gem. Smithsonite has a high zinc content of about 52%. Smithsonite is available from many localities worldwide.
| Category: | Carbonate mineral |
| Formula: | ZnCO3 |
| zinc carbonate | |
| Crystallography: | Trigonal – Hexagonal Scalenohedral |
| Crystal Habit: | Uncommon as crystals, to 10 cm, rhombohedral and scalenohedral; additional modifying forms, with curved faces; typically botryoidal, reniform, spherulitic; stalactitic, and as cave pearls; earthy, friable, granular to porous or compact massive. |
| Twinning: | Rarely |
| Cleavage: | [1011] Perfect, [1011] Perfect, 1011 Perfect |
| Fracture: | Uneven to Conchoidal |
| Tenacity: | Brittle |
| Moh’s Hardness: | 4.0 – 4.5 |
| Density: | 4.42- 4.44 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Other: | Effervesces in warm acids |
| Color: | White, grey, yellow, green to apple-green, blue, pink, purple, bluish grey, and brown |
| Transparency: | Transparent to Translucent |
| Luster: | Vitreous to Pearly |
| Refractive Index: | 1.619 – 1.850 Uniaxial ( – ) |
| Birefringence: | 0.223 – 0.227 (high) |
| Dispersion: | 0.037 (high) |
| Pleochroism: | Colorless |
