| Russellite | |
|---|---|
 Yellow globular aggregates of the rare tungsten mineral russellite from the famous Clara Mine (Wolfach, Black Forest, Baden-Württemberg, Germany). | |
| General | |
| Category | Tungstate minerals |
| Formula (repeating unit) | Bi2WO6 |
| IMA symbol | Rll[1] |
| Strunz classification | 4.DE.15 |
| Crystal system | Orthorhombic |
| Crystal class | Pyramidal (mm2) H-M symbol: (mm2) |
| Space group | Pca21 |
| Unit cell | a = 5.43 Å, b = 16.43 Å c = 5.45 Å; Z = 4 |
| Identification | |
| Color | Yellow-green, yellow |
| Crystal habit | Fine-grained, compact, massive |
| Mohs scale hardness | 3.5 |
| Specific gravity | 7.33–7.37 |
| Optical properties | Biaxial (+) |
| Refractive index | 2.17–2.51 |
| Dispersion | Relatively strong |
| References | [2][3][4] |
Russellite is a bismuth tungstate mineral with the chemical formula Bi2WO6.[2] It crystallizes in the orthorhombic crystal system. Russellite is yellow or yellow-green in color, with a Mohs hardness of 3+1⁄2.[2]
Russellite is named for the mineralogist Sir Arthur Russell, and the type locality is the Castle-an-Dinas Mine,[2] near St Columb Major in Cornwall, where it was found in 1938 in wolframite.[5] It occurs as a secondary alteration of other bismuth bearing minerals in tin−tungsten hydrothermal ore deposits, pegmatites and greisens. It typically occurs associated with native bismuth, bismuthinite, bismite, wolframite, ferberite, scheelite, ferritungstite, anthoinite, mpororoite, koechlinite, cassiterite, topaz, muscovite, tourmaline and quartz.[3]
