Danalite
Danalite is an iron beryllium silicate sulfide mineral with formula: Fe2+4Be3(SiO4)3S.
| Danalite | |
|---|---|
 | |
| General | |
| Category | Sodalite - Feldspathoid |
| Formula (repeating unit) | Fe2+4Be3(SiO4)3S |
| Strunz classification | 9.FB.10 |
| Dana classification | 76.02.04.02 |
| Crystal system | Isometric |
| Crystal class | Hextetrahedral (43m) H-M symbol: (4 3m) |
| Space group | P43n |
| Identification | |
| Color | Yellow, pink, reddish brown, red: colorless to pink in thin section |
| Crystal habit | Octahedral and dodecahedral crystals, typically massive or as segregations |
| Cleavage | {111} and {111} |
| Fracture | Subconchoidal to uneven |
| Tenacity | Brittle |
| Mohs scale hardness | 5.5 to 6 |
| Luster | Vitreous or greasy |
| Streak | Grey white |
| Diaphaneity | Semitransparent |
| Specific gravity | 3.28 - 3.46 |
| Optical properties | Isotropic |
| Refractive index | n = 1.747 - 1.771 |
| References | [1][2][3] |
It is a rare mineral which occurs in granites, tin bearing pegmatites, contact metamorphic skarns, gneisses and in hydrothermal deposits. It occurs in association with magnetite, garnet, fluorite, albite, cassiterite, pyrite, muscovite, arsenopyrite, quartz, and chlorite.[1]
Danalite was first described in 1866 from a deposit in Essex County, Massachusetts and named for American mineralogist James Dwight Dana (1813–1895).[3]
It has been found in Massachusetts, New Hampshire, Sierra County, New Mexico; Yavapai County, Arizona; Needlepoint Mountain, British Columbia; Walrus Island, James Bay, Quebec; Sweden; Cornwall, England; Imalka and Transbaikal, Russia; Kazakhstan; Somalia; Tasmania; Western Australia and Hiroshima Prefecture, Japan.[1][2]
References
- http://rruff.geo.arizona.edu/doclib/hom/danalite.pdf Handbook of Mineralogy
- http://www.mindat.org/min-1341.html Mindat.org
- http://webmineral.com/data/Danalite.shtml Webmineral data