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 (ō-tŭn′īt′, ô′tə-nīt)
A yellowish, fluorescent minor ore of uranium with the composition Ca(UO2)2(PO4)2·10-12H2O.

[After Autun, a city of east-central France.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Minerals) a yellowish fluorescent radioactive mineral consisting of a hydrated calcium uranium phosphate in tetragonal crystalline form. It is found in uranium ores. Formula: Ca(UO2)2(PO4)2.10–12H2O
[C19: named after Autun in France, one of the places where it was found, + -ite1]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˈɔt nˌaɪt, oʊˈtʌn aɪt)

a yellow mineral, a hydrous calcium uranium phosphate, CaU2P2O12∙8H2O, a minor ore of uranium.
[1850–55; after Autun, city in E France near source of supply; see -ite1]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
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References in periodicals archive ?
The Gaussian-Lorentz model was developed and validated by empirical studies of isolated vibration absorption bands in both transmission and reflectance spectra of autunite, nontronite, and smectite [25,26].
Uranium is found in hundreds of minerals, including uraninite (the most common uranium ore), carnotite, autunite, uranophane, torbernite and coffinite.
You'll be understanding if, when you obtain a copy of the book, you turn to the Santa Tereza chrysoberyl (page 106: Keith Proctor collection), Morro Velho gold (page 150: Alvaro Lucio collection), Lavra Caba Saco rutile (page 288: Luiz Menezes collection), Brumado dolomite (page 317: Julio Landmann collection), Ouro Preto crocoite (page 331: Alvaro Lucio collection), Sapo mine fluorapatite (page 347: Jim and Gail Spann collection), Malacacheta autunite (page 357: Luiz Menezes collection), or nearly any one of the stunning specimens of topaz, elbaite, beryl, euclase, etc.
2) uranium occurs as the U-phosphate minerals torbenite, autunite, and Pb-metaautunite (MacDonald 2001).
SEM observations showed evidence of secondary uranium minerals such as autunite, saleeite, coffinite, phosphouraninite, and uranotile.
At the Southern Fault (102.67 m) the presence of autunite, indicative of oxidizing conditions, and the presence of U-silicophosphates, indicative of more reducing conditions, seems to indicate that it is a transition redox zone in the oxidation of U(IV) to U(VI), although their coexistence with altered pyrite indicates dominant oxidizing conditions.
The other associated hydrothermal minerals are epidore, titanite, chlorite, muscovite, tourmaline, and minor amounts of opaque minerals such as sphalerite, chalcopyrite, uraninite, and autunite. The most characteristic feature of the altered rocks is brittle deformation and pervasive degradation of plagioclase and biotite.
The Maritime Alps host the most famous Italian deposits of uranium minerals (Lurisia, Peveragno, Bric Colme) where autunite was discovered in 1913.
(1991) Two autunite localities in northeastern Washington.
In the June installment of "what's new in the mineral world," my online column on the Mineralogical Record website (, I described the exciting October 2005 discovery of superb autunite specimens in a uraniferous pegmatite worked by the Nossa Senhora do Assuncao mine, near Ferreira de Aves, Viseu, Portugal--and the picture accompanying the report shows that these new autunites rival even the best of the old ones from the Daybreak mine, Washington and the Streuberg quarry, Germany.