Hectorite

Hectorite
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 is a rare soft, greasy, white clay mineral with a chemical formula of Na_0.3(Mg,Li)₃Si₄O₁₀(OH)₂.^[2]

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]

See also

• Classification of minerals
• List of minerals
• Saponite – Trioctahedral phyllosilicate mineral

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. Anthony JW, Bideaux RA, Bladh KW, et al. (1995). "Hectorite" (PDF). Handbook of mineralogy. Tucson, Ariz.: Mineral Data Publishing. ISBN 9780962209734. OCLC 20759166.
3. "Hectorite Mineral Data". webmineral.com. Retrieved 3 Apr 2019.
4. Jololyn R (2007). "Hectorite: Mineral information, data and localities". www.mindat.org. Retrieved 3 Apr 2019.
5. Benhammou A, Tanouti B, Nibou L, et al. (2009). "Mineralogical and Physicochemical Investigation of Mg-Smectite from Jbel Ghassoul, Morocco". Clays and Clay Minerals. 57 (2): 264–270. Bibcode:2009CCM....57..264B. doi:10.1346/CCMN.2009.0570212. S2CID 95505225.
6. Bradley, Dwight C.; Stillings, Lisa L.; Jaskula, Brian W.; Munk, LeeAnn; McCauley, Andrew D. (2017). Lithium, Chapter K of Critical Mineral Resources of the United States—Economic and Environmental Geology and Prospects for Future Supply (PDF) (Report). United States Geological Survey.
7. Moores S (2007). "Between a rock and a salt lake". Industrial Minerals. 477: 58–69.