Daubréeite

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For the iron chromium sulfide mineral see Daubréelite
Daubréeite
General
Category Oxide mineral
Formula
(repeating unit)
BiO(OH,Cl)
Strunz classification 03.DC.25
Crystal symmetry Tetragonal ditetragonal dipyramidal
H-M symbol: (4/m2/m2/m)
Space group: P4/nmm
Unit cell a = 3.85 Å, c = 7.4 Å; Z=2
Identification
Color Creamy-white, grayish, yellowish-brown
Crystal habit Compact massive, columnar
Crystal system Tetragonal
Cleavage [{001}, perfect
Tenacity Very plastic, sectile
Mohs scale hardness 2-2.5
Luster Greasy, silky
Diaphaneity Transparent to translucent
Specific gravity 6-6.5
Optical properties Uniaxial (-)
Refractive index nω = 2.150 nε = 1.910
Birefringence δ = 0.240
References [1][2][3]

Daubréeite is a rare bismuth oxidehalide mineral with formula BiO(OH,Cl). It is a creamy-white to yellow-brown, soft, earthy clay–like mineral which crystallizes in the tetragonal crystal system. It is a member of the matlockite group.[1]

It was first described for an occurrence in the Constanicia mine, Tazna, Bolivia, in 1876.[4] It was named for French mineralogist Gabriel Auguste Daubrée (1814–1896).[1] At the Tanza location it occurs as a secondary mineral formed by the oxidation of native bismuth or bismuthinite. It occurs with clay minerals.[3] In addition to its discovery location it has also been reported from the Tintic District in the East Tintic Mountains of Juab County, Utah; in the Josephine Creek District of Josephine County, Oregon; in the Manhattan District of Nye County, Nevada; and the Rio Marina Mine on Elba Island, Italy.[1]

References[edit]