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.^[3] Associated minerals include priceite, meyerhofferite, colemanite, hydroboracite, ulexite and gypsum.^[2][3]

Inyoite
General
Category	Nesoborates
Formula (repeating unit)	CaB3O3(OH)5·4H2O
IMA symbol	Iyo^[1]
Strunz classification	6.CA.35
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P21/a
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
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	^[2]^[3]

References

1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
2. Mindat.org
3. Handbook of Mineralogy

 

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