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Phyllosilicate clay mineral From Wikipedia, the free encyclopedia
Hectorite is a rare soft, greasy, white clay mineral with a chemical formula of Na0.3(Mg,Li)3Si4O10(OH)2.[2]
Hectorite | |
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![]() Hectorite from California | |
General | |
Category | Phyllosilicates Smectite |
Formula (repeating unit) | Na0.3(Mg,Li)3Si4O10(OH)2 (empirical: Na3(Mg,Li)30Si40O100(OH)20) |
IMA symbol | Htr[1] |
Strunz classification | 9.EC.45 |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) (same H-M symbol) |
Space group | C2/m |
Unit cell | a = 5.25 Å, b = 9.18 Å c = 16 Å; β = 99°; Z = 2 |
Identification | |
Color | White, cream, pale brown, mottled |
Crystal habit | Thin laths and aggregates |
Cleavage | [001] Perfect |
Fracture | Uneven |
Mohs scale hardness | 1–2 |
Luster | Earthy to waxy |
Streak | White |
Diaphaneity | Translucent to opaque |
Specific gravity | 2–3 |
Optical properties | Biaxial (−) – 2V small |
Refractive index | nα = 1.490 nβ = 1.500 nγ = 1.520 |
Birefringence | δ = 0.030 |
References | [2][3][4] |
Hectorite was first described in 1941 and named for an occurrence in the United States near Hector (in San Bernardino County, California,[4] 30 miles east of Barstow.) Hectorite occurs with bentonite as an alteration product of clinoptilolite from volcanic ash and tuff with a high glass content.[2] Hectorite is also found in the beige/brown clay ghassoul, mined in the Atlas Mountains in Morocco.[5] A large deposit of hectorite is also found at the Thacker Pass lithium deposit, located within the McDermitt Caldera in Nevada. The Thacker Pass lithium deposit could be a significant source of lithium.[6]
Despite its rarity, it is economically viable as the Hector mine sits over a large deposit of the mineral. Hectorite is mostly used in making cosmetics, but has uses in chemical and other industrial applications, and is a mineral source for refined lithium metal.[7]