aluniten.
/ˈal(j)ᵿnʌɪt/, U.S. /ˈæl(j)əˌnaɪt/ Mineralogy.
A mineral which was historically an important source of alum and is now mined for potassium and aluminium, and which occurs in granular or compact masses and also as tabular or rhombohedral crystals, colourless when pure but often yellowish or reddish-brown owing to impurities. Cf. alum stone n. at alum n.1 Compounds 3.Alunite is a basic sulphate of potassium and aluminium, KAl3(SO4)2(OH)6. Crystal system: trigonal.
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the world > the earth > minerals > types of mineral > sulphates > [noun] > alunite
alum stone1651
aluminilite1804
alunite1821
alumite1826
1821 Synopsis Contents Brit. Mus. (ed. 18) 35 It must not be confounded with alum-stone (alunite of French mineralogists), which, according to Cordier, is a hydrate of alumine with anhydrous sulphates of alumine and potash.
1823 tr. F. S. Beudant Trav. Hungary xiii. 109 Fragments are found partly in a siliceous state, and partly in the state of compact alunite.
1875 R. Hunt & F. W. Rudler Ure's Dict. Arts (ed. 7) I. 109 The alum-stone or alunite is a mineral of limited occurrence, being found in moderate quantity at Tolfa (near Civita Vecchia).
1910 Encycl. Brit. I. 773/1 Distinct crystals of alunite are rarely met with in cavities in the massive material.
1952 A. M. Smith Manures & Fertilisers vii. 175 Alunite, obtained from a series of nearly dry lakes in Western Australia, has been processed to give potassium sulphate.
1989 J. E. Christensen in R. D. Poll Utah's Hist. xxvii. 503 Demand for aluminum airplanes spurred the Office..to authorize three million dollars for construction of a mill in Salt Lake City to process alunite.
2001 P. Ball Bright Earth iii. 65 An alum shortage..was later relieved by the discovery of deposits of alunite.
This entry has been updated (OED Third Edition, September 2012; most recently modified version published online March 2022).
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n.1821