| Daubréeite | |
| Category: | Oxide mineral |
| Imasymbol: | Dau[1] |
| Strunz: | 3.DC.25 |
| System: | Tetragonal |
| Class: | Ditetragonal dipyramidal (4/mmm) H-M symbol: (4/m 2/m 2/m) |
| Symmetry: | P4/nmm |
| Unit Cell: | a = 3.85, c = 7.4 [Å]; Z = 2 |
| Color: | Creamy-white, grayish, yellowish-brown |
| Habit: | Compact massive, columnar |
| Cleavage: | [{001}, perfect | fracture = | tenacity = Very plastic, sectile | mohs = 2-2.5 | luster = Greasy, silky | streak = | diaphaneity = Transparent to translucent | gravity = 6-6.5 | density = | polish = | opticalprop = Uniaxial (-) | refractive = n<sub>ω</sub> = 2.150 n<sub>ε</sub> = 1.910 | birefringence = δ = 0.240 | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | references = <ref name=Mindat>[http://www.mindat.org/min-1229.html Daubréeite on Mindat][2] [3] |
Daubréeite is a rare bismuth oxohalide mineral with formula . 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.
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). 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, Italy.