Sassolite

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Sassolite
Sassolite.jpg
Yellow sassolite
General
CategoryBorate mineral
Formula
(repeating unit)
H3BO3
Strunz classification6.AA.05
Crystal systemTriclinic
Crystal classPinacoidal (1)
(same H-M symbol)
Space groupP1
Unit cella = 7.02 Å, b = 7.06 Å
c = 6.59 Å; α = 103.65°
β = 101.11°, γ = 59.98°; Z = 4
Identification
ColourWhite to gray, may be pale yellow from included sulfur or pale brown from included iron oxides; colourless in transmitted light
Crystal habitAs scaly pseudohexagonal crystals; ncrustations; platy; tabular; may be stalactitic
TwinningAround [001] as twin axis, common
CleavagePerfect on {001}, micaceous
TenacitySectile
Mohs scale hardness1
LustreVitreous to pearly
StreakWhite
DiaphaneityTransparent
Specific gravity1.46-1.50
Optical propertiesBiaxial (-)
Refractive indexnα = 1.340 nβ = 1.456 nγ = 1.459
Birefringenceδ = 0.119
2V angleMeasured: 5°, Calculated: 16°
SolubilitySoluble in water
References[1][2][3]

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 evaporite deposits.[1]

Its mineral form was first described in 1800, and was named after Sasso Pisano, Castelnuovo Val di Cecina, Pisa Province, Tuscany, Italy where it was found.[3] The mineral may be found in lagoons throughout Tuscany and Sasso.[2] 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.[1]

See also[edit]

References[edit]

External links[edit]

Media related to Sassolite at Wikimedia Commons