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Tusionite
Tusionite, a rare gem found in Tajikistan
General
Category	Borate minerals
Formula (repeating unit)	MnSn(BO3)2
IMA symbol	Tsn
Strunz classification	6.AA.15
Crystal system	Trigonal
Crystal class	Rhombohedral (3) H-M symbol: (3)
Space group	R3 (no. 148)
Identification
Formula mass	291.26 gm
Color	Colorless, light yellow to yellow brown
Crystal habit	Thin platy crystals in rosettes
Cleavage	Perfect
Mohs scale hardness	5–6
Luster	Vitreous
Streak	white
Diaphaneity	Translucent
Density	4.73
Optical properties	Uniaxial (−)
Refractive index	nω = 1.854 nε = 1.752
Birefringence	δ = 0.102
Pleochroism	Orange yellow
References

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 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

1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
2. Mineralienatlas
3. http://www.webmineral.com/data/Tusionite.shtml Webmineral data
4. http://www.mindat.org/min-4062.html Mindat w/ location data
5. http://rruff.geo.arizona.edu/doclib/hom/tusionite.pdf Mineral Handbook

v t e Manganese minerals
Borates	Sussexite Tusionite
Carbonates	Ankerite Kutnohorite Rhodochrosite Manganoan calcite
Oxides	Simple Hausmannite Manganite Manganosite Nsutite Pyrolusite Mixed Birnessite Bixbyite Ferrocolumbite Ferrotantalite Galaxite Jacobsite Manganotantalite Psilomelane (calvonigrite) Romanèchite Tantalite Todorokite Umber
Phosphates	Childrenite Graftonite Lithiophilite Natrophilite Purpurite Triplite Triploidite Zanazziite
Silicates	Babingtonite Braunite Brownleeite Calderite Chloritoid Eudialyte Glaucochroite Jeffersonite Knebelite Ottrelite Piemontite Pyroxferroite Rhodonite Spessartine Sugilite Tephroite Zakharovite Zircophyllite
Sulfides	Alabandite Hauerite Rambergite
Other	Axinite (borosilicate) Geigerite (arsenate) Manganese nodule (various) Samsonite (sulfosalt) Zincobotryogen (sulfate) Wolframite (tungstate) Hübnerite (tungstate)
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