Inyoite Locality: U.S. Borax open pit (Boron pit), U.S. Borax Mine (Pacific West Coast Borax; Pacific Coast Borax Co.; Boron Mine; U.S. Borax and Chemical Corp. — Photo: Rock Currier · CC BY 3.0
Inyoite
A colorless hydrated calcium borate discovered in 1914 in California's Inyo County — it turns white as it dries.
Intro adapted from Wikipedia (CC BY-SA).
Inyoite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula CaB₃O₃(OH)₅·4H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/a).
Key properties: Mohs hardness 2; specific gravity 1.875; typically colorless or white or yellow; white streak; Vitreous luster; refractive index 1.508; optically biaxial.
IMA symbol Iyo, grandfathered status — known before the IMA’s founding, named in 1914.
Along fractures and nodular in sedimentary borate deposits; may be authigenic in playa sediments.
It is found associated with Meyerhofferite, colemanite, priceite, hydroboracite, ulexite, gypsum.
The name refers to Inyo Co., California, USA, wherein the first specimens were collected.
Collections: Collector Favorites, Rare & Remarkable.