Yttrocrasite-(Y)
Yttrocrasite-(Y) is a very rare radioactive mineral. The chemical formula of Yttrocrasite-(Y) is (Y,Th,Ca,U)(Ti,Fe)2(O,OH)6 and its molecular weight is 298.05 gm. Faceted gems are extremely rare and really only faceted as a collector’s oddity. Yttrocrasite-(Y) has a specific gravity of 4.80 (g/cm3) and the refractive index of n = 2.12 – 2.15 Isotropic. Yttrocrasite-(Y) is strongly radioactive due to the presence of Thorium (7.79%) and Uranium (7.99%).
There are only a few locations for finding Yttrocrasite-(Y): Chudnoe Pd-Au deposit, Grubependity lake, Komi Republic, Northern Region, Russia; Åskagen (Torskebäcken), Filipstad, Värmland, Sweden; and the Type Locality of Clear Creek pegmatite, Burnet County, Texas, USA.
| Chemical Formula: | (Y,Th,Ca,U)(Ti,Fe)2(O,OH)6 |
| Molecular Weight: | 298.05 gm |
| Crystallography: | Orthorhombic or Amorphous. Metamict (may have been orthorhombic before metamictisation). |
| Crystal Habit: | Crystals rough, showing three pinacoids, a prism, and an orthodome. |
| Twinning: | None |
| Cleavage: | None |
| Fracture: | Irregular/Uneven, Sub-Conchoidal |
| Tenacity: | Brittle |
| Hardness (Mohs): | 5.5 – 6.0 |
| Density: | 4.80 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Strong; GRapi = 784,722.58 (Gamma Ray American Petroleum Institute Units) |
| Color: | Black, Brown where altered; in transmitted light, Amber-Yellow to light Yellow |
| Transparency: | Opaque. Translucent on thin edges |
| Luster: | Resinous |
| Refractive Index: | n = 2.12 – 2.15 Isotropic |
| Birefringence: | 0.00 (Isotropic) |
| Dispersion: | Strong |
| Pleochroism: | None |
| Anisotrophism: | Weakly anisotropic in part |
