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alunite

[al-yuh-nahyt] /ˈæl yəˌnaɪt/
noun
1.
a mineral, a hydrous sulfate of potassium and aluminum, KAl 3 (SO 4) 2 (OH) 6 , commonly occurring in fine-grained masses.
Also called alumstone
[al-uh m-stohn] /ˈæl əmˌstoʊn/ (Show IPA)
.
Origin
1865-1870
1865-70; < French alun (< Latin alūmen alum1) + -ite1
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Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for alum stone

alunite

/ˈæljʊˌnaɪt/
noun
1.
a white, grey, or reddish mineral consisting of hydrated aluminium sulphate. It occurs in volcanic igneous rocks and is a source of potassium and aluminium compounds. Formula: KAl3(SO4)2(OH)6
Word Origin
C19: from French alun alum (from Latin alūmen) + -ite1
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Encyclopedia Article for alum stone

a widespread rock-forming sulfate mineral that occupies pockets or seams in volcanic rocks such as rhyolites, trachytes, and andesites, where it presumably formed through their chemical reaction with escaping sulfurous vapours. It has been used as a source of potash (during World War I) and as a source of alumina (during World War II); in Europe it was once used extensively to make potash alum, and it has been mined for this purpose since the 15th century. Large deposits exist near Beregovo, Ukraine; Almeria, Spain; and Bullah Delah in New South Wales, Australia. For chemical formula and physical properties, see sulfate mineral (table)

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Word Value for alum

6
9
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