Daubréeite: Properties and Occurrences

Daubréeite is a rare bismuth oxohalide mineral with formula BiO(OH, Cl). It is a sulphide of chromium observed in some meteoric irons. 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 Constancia mine, Tazna, Bolivia, in 1876.[4] It was named for French mineralogist Gabriel Auguste Daubrée (1814–1896).

General Information

  • Category: Oxide mineral
  • Formula: BiO(OH, Cl)
  • Crystal system: Tetragonal
  • Crystal class: Ditetragonal dipyramidal (4/mmm)

Properties

  • Color: Creamy-white, grayish, yellowish-brown
  • Crystal habit: Compact massive, columnar
  • 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 (-)

Occurrence: A secondary mineral formed by alteration of bismuth or bismuthinite, intermixed with “clay” (Tazna, Bolivia).

At the Tanza location, it occurs as a secondary mineral formed by the oxidation of native bismuth or bismuthinite. It occurs with clay minerals. 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.

 

Information Source: