Article · Wikipedia archive · Last revised Jun 15, 2026

Inyoite

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. Associated minerals include priceite, meyerhofferite, colemanite, hydroboracite, ulexite and gypsum.

Last revised
Jun 15, 2026
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Inyoite
General
CategoryNesoborates
FormulaCaB3O3(OH)5·4H2O
IMA symbolIyo1
Strunz classification6.CA.35
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupP21/a
Unit cella = 10.63, b = 12.06
c = 8.4 [Å]; β = 114.03°; Z = 4
Identification
ColourColourless, white on dehydration.
Crystal habitCommonly as prismatic to tabular crystals; also in cockscomb aggregates of pseudorhombohedral crystals; coarsely spherulitic or granular
CleavageGood on {001}, distinct on {010}
FractureIrregular/uneven
TenacityBrittle
Mohs scale hardness2
LustreVitreous
Specific gravity1.875
Optical propertiesBiaxial (−)
Refractive indexnα = 1.495 nβ = 1.505 – 1.512 nγ = 1.520
BirefringenceMaximum δ = 0.025
DispersionWeak
References23

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.3 Associated minerals include priceite, meyerhofferite, colemanite, hydroboracite, ulexite and gypsum.23

References

References