Tusionite
Tusionite is a rare colorless to transparent to translucent yellow brown trigonal borate mineral with chemical formula: MnSn(BO3)2. The mineral is composed of 18.86% manganese, 40.76% tin, 7.42% boron, and 32.96% oxygen. It is a late stage hydrothermal mineral and occurs rarely in granite pegmatites in miarolitic cavities.
| Tusionite | |
|---|---|
 | |
| General | |
| Category | Borate minerals |
| Formula (repeating unit) | MnSn(BO3)2 |
| Strunz classification | 6.AA.15 |
| Crystal system | Trigonal |
| Crystal class | Rhombohedral (3) H-M symbol: (3) |
| Space group | R(3) |
| Identification | |
| Color | Colorless, light yellow to yellow brown |
| Crystal habit | Thin platy crystals in rosettes |
| Cleavage | [001] Perfect |
| Mohs scale hardness | 5-6 |
| Luster | Vitreous |
| Streak | white |
| Diaphaneity | Translucent |
| Specific gravity | 4.73 |
| Optical properties | Uniaxial (-) |
| Refractive index | nω = 1.854 nε = 1.752 |
| Birefringence | δ = 0.102 |
| References | [1][2][3][4] |
Tusionite was named for the location where the mineral was first discovered and described in 1983 in the Tusion River Valley in the Pamir Mountains of Tajikistan. Tusionite has also been reported from Recice in the Czech Republic and in pegmatites at Thomas Mountain, Riverside County, California.
See also
- Classification of minerals
- List of minerals
References
- Mineralienatlas
- http://www.webmineral.com/data/Tusionite.shtml Webmineral data
- http://www.mindat.org/min-4062.html Mindat w/ location data
- http://rruff.geo.arizona.edu/doclib/hom/tusionite.pdf Mineral Handbook
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