Tusionite

Infobox mineral
name = Tusionite
category = Borate mineral
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boxbgcolor =


caption =
formula = MnSn(BO_{3)2
molweight =
color = Colorless, light yellow to yellow brown
habit = Thin platy crystals in rosettes
system = Trigonal
twinning =
cleavage = [001] Perfect
fracture =
mohs = 5-6
luster = Vitreous
refractive = nω = 1.854 nε = 1.752
opticalprop = Uniaxial (-)
birefringence = δ = 0.102
pleochroism =
streak = white
gravity = 4.73
melt =
fusibility =
diagnostic =
solubility =
diaphaneity = Translucent
other =
references = [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]}

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.

References