Hectorite

{{Short description|Phyllosilicate clay mineral}}

{{Infobox mineral

| name = Hectorite

| category = Phyllosilicates
Smectite

| image = Hectorite Hydrous magnesium iron silicate Hector, California.jpg

| imagesize = 200

| caption = Hectorite from California

| formula = Na_0.3(Mg,Li)₃Si₄O₁₀(OH)₂
(empirical: Na₃(Mg,Li)₃₀Si₄₀O₁₀₀(OH)₂₀)

| IMAsymbol = Htr{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}

| strunz = 9.EC.45

| system = Monoclinic

| class = Prismatic (2/m)
(same H-M symbol)

| symmetry = C2/m

| unit cell = a = 5.25 Å, b = 9.18 Å
c = 16 Å; β = 99°; Z = 2

| color = White, cream, pale brown, mottled

| habit = Thin laths and aggregates

| twinning =

| cleavage = [001] Perfect

| fracture = Uneven

| mohs = 1–2

| luster = Earthy to waxy

| refractive = n_α = 1.490 n_β = 1.500 n_γ = 1.520

| opticalprop = Biaxial (−) – 2V small

| birefringence = δ = 0.030

| pleochroism =

| streak = White

| gravity = 2–3

| density =

| melt =

| fusibility =

| diagnostic =

| solubility =

| diaphaneity = Translucent to opaque

| other =

| references = {{Cite web|url=http://webmineral.com/data/Hectorite.shtml|title=Hectorite Mineral Data|website=webmineral.com|access-date=3 Apr 2019}}

}}

Hectorite is a rare soft, greasy, white clay mineral with a chemical formula of {{Chem2|Na0.3(Mg,Li)3Si4O10(OH)2}}.{{Cite book|title=Handbook of mineralogy|vauthors=Anthony JW, Bideaux RA, Bladh KW, Nichols MC|publisher=Mineral Data Publishing|year=1995|isbn=9780962209734|location=Tucson, Ariz.|chapter=Hectorite|oclc=20759166|display-authors=3|chapter-url=http://rruff.info/doclib/hom/hectorite.pdf}}

Hectorite was first described in 1941 and named for an occurrence in the United States near Hector, California (in San Bernardino County, California,{{Cite web|url=https://www.mindat.org/min-1841.html|title=Hectorite: Mineral information, data and localities.|last=Jololyn R|date=2007|website=www.mindat.org|access-date=3 Apr 2019}} 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. Hectorite is also found in the beige/brown clay ghassoul, mined in the Atlas Mountains in Morocco.{{cite journal|display-authors=3|vauthors=Benhammou A, Tanouti B, Nibou L, Yaacoubi A, Bonnet JP|date=2009|title=Mineralogical and Physicochemical Investigation of Mg-Smectite from Jbel Ghassoul, Morocco|journal=Clays and Clay Minerals|volume=57|issue=2|pages=264–270|bibcode=2009CCM....57..264B|doi=10.1346/CCMN.2009.0570212|s2cid=95505225}} 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.{{cite report | url=https://pubs.usgs.gov/pp/1802/k/pp1802k.pdf | title = Lithium, Chapter K of Critical Mineral Resources of the United States—Economic and Environmental Geology and Prospects for Future Supply | first1 = Dwight C. | last1 = Bradley | first2 = Lisa L. | last2 = Stillings | first3 = Brian W. | last3 = Jaskula | first4 = LeeAnn | last4 = Munk | first5 = Andrew D. | last5 = McCauley | year = 2017 | number = Professional Paper 1802–K | publisher = United States Geological Survey}}

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.{{Cite journal|vauthors=Moores S|date=2007|title=Between a rock and a salt lake|journal=Industrial Minerals|volume=477|pages=58–69}}