Sassolite

Infobox mineral
name = Sassolite
category =
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caption = Yellow sassolite
formula = H₃BO₃
molweight =
color = White to gray; yellow; brown; colourless
habit = Encrustations; platy; tabular
system = Triclinic-pinacoidal
twinning =
cleavage = Perfect, micaceous
fracture = Sectile
mohs = 1
luster = Vitreous to pearly
refractive = 1.340-1.459
opticalprop =
birefringence =
pleochroism = None - colourless
streak = White
gravity = 1.46-1.5
melt =
fusibility =
diagnostic =
solubility = Soluble in water
diaphaneity =
other =

Sassolite is a borate mineral, and is the mineral form of boric acid. It occurs in volcanic fumaroles and hot springs, as well as in bedded sedimentary borate deposits. Its mineral form was first noted in the early 19th century, and was named after Sasso, Italy, where it was found. Usually coloured white to gray, it is colourless in transmitted light, and can also take on a yellow colour from sulfur impurities, or brown from iron oxides.

"See the boric acid entry for additional information."

References

* [http://www.mindat.org/min-3540.html MinDAT]
* [http://webmineral.com/data/Sassolite.shtml Webmineral]
* [http://rruff.geo.arizona.edu/doclib/hom/sassolite.pdf Handbook of Mineralogy] (PDF)