Wiluite
Wiluite is a very rare variety of Vesuvianite that was discovered in 1997 in the Wilui River Valley of the Eastern-Siberian Region of Russia. It is a very complex silicate mineral containing calcium, aluminum, magnesium, iron, titanium and boron in addition to the basic silicate minerals. Wiluite crystals are usually well-formed euhedrals of dark green color and are translucent to opaque.
Wiluite is only known from two locations, the type locality at the Vilyui River Basin (Vilui River Basin; Wilui River Basin), Saha Republic (Sakha Republic; Yakutia), Eastern-Siberian Region, Russia; and a very minor source at Ariccia, Latium, Italy.
| Chemical Formula: | Ca19(Al,Mg,Fe,Ti)13(B,Al,[ ])5Si18O68(O,OH)10 |
| Calcium Aluminum Magnesium Iron Titanium Boron Silicate Hydroxide | |
| Molecular Weight: | 2,924.83 gm |
| Composition: | Calcium | 26.04 % | Ca | 36.43 % | CaO |
| Magnesium | 3.99 % | Mg | 6.61 % | MgO | |
| Titanium | 0.82 % | Ti | 1.37 % | TiO2 | |
| Aluminum | 6.46 % | Al | 12.20 % | Al2O3 | |
| Iron | 1.72 % | Fe | 2.46 % | Fe2O3 | |
| Silicon | 17.28 % | Si | 36.98 % | SiO2 | |
| Boron | 0.96 % | B | 3.09 % | B2O3 | |
| Hydrogen | 0.07 % | H | 0.62 % | H2O | |
| Oxygen | 42.67 % | O | |||
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Tetragonal – Ditetragonal Dipyramidal |
| Crystal Habit: | Euhedral Crystals; occurs as well-formed crystals showing good external form. |
| Twinning: | None |
| Cleavage: | {100} Poor |
| Fracture: | Irregular/Uneven |
| Tenacity: | Brittle |
| Moh’s Hardness: | 6.0 |
| Density: | 3.36 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Color: | Dark Green |
| Transparency: | Translucent to Opaque |
| Luster: | Vitreous |
| Refractive Index: | 1.721 – 1.725 Uniaxia ( + ) |
| Birefringence: | 0.004 |
| Dispersion: | Very high |
| Pleochroism: | Very Strong |
