Inyoite

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Inyoite
Inyoite.jpg
General
Category Nesoborates
Formula
(repeating unit)
CaB3O3(OH)5·4H2O
Strunz classification 6.CA.35
Crystal system Monoclinic
Prismatic class
Unit cell a = 10.63, b = 12.06
c = 8.4 [Å]; β = 114.03°; Z = 4
Identification
Colour Colourless, white on dehydration.
Crystal habit Commonly as prismatic to tabular crystals; also in cockscomb aggregates of pseudorhombohedral crystals; coarsely spherulitic or granular
Crystal symmetry Monoclinic
H-M symbol: (2/m)
Space group: P21/a
Cleavage Good on {001}, distinct on {010}
Fracture Irregular/uneven
Tenacity Brittle
Mohs scale hardness 2
Lustre Vitreous
Specific gravity 1.875
Optical properties Biaxial (-)
Refractive index nα = 1.495 nβ = 1.505 - 1.512 nγ = 1.520
Birefringence Maximum δ = 0.025
Dispersion Weak
References [1][2]

Inyoite, named after Inyo County, California, where it was discovered in 1914, is a colourless monoclinic mineral. It turns white on dehydration. Its chemical formula is Ca(H4B3O7)(OH)·4H2O or CaB3O3(OH)5·4H2O.[2]

Inyoite, 3 cm. crystal, from Monte Azul deposit, Sijes, Salta Province, Argentina.

References[edit]