Sassolite

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Sassolite

Yellow sassolite
General
Category Mineral
Chemical formula H3BO3
Identification
Color White to gray; yellow; brown; colourless
Crystal habit Encrustations; platy; tabular
Crystal system Triclinic-pinacoidal
Cleavage Perfect, micaceous
Fracture Sectile
Mohs Scale hardness 1
Luster Vitreous to pearly
Refractive index 1.340-1.459
Pleochroism None - colourless
Streak White
Specific gravity 1.46-1.5
Solubility Soluble in water

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.

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