Derriksite: Properties and Occurrences

Derriksite is an orthorhombic-pyramidal mineral containing copper, hydrogen, oxygen, selenium, and uranium. It is a very rare uranium mineral with the chemical formula Cu4(UO2)(SeO3)2(OH)6•H2O. It is a secondary mineral that contains copper, uranium and the rarer selenium. It is a bright green to duller bottle green color. It is quite radioactive.

It is named after Jean Marie Francois Joseph Derriks (1912–1992), geologist and administrator of the Union Minière du Haut Katanga (UMHK).

General Information

  • Category: Oxide minerals
  • Formula: Cu4(UO2)(SeO3)2(OH)6H2O
  • Crystal system: Orthorhombic
  • Crystal class: Pyramidal (mm2)

Properties

Its crystal habit is acicular, it is most likely to be found along with the uranyl selenium mineral demesmaekerite, but derriksite is much rarer than demesmaekerite. It has a Mohs hardness of about 2.

  • Color: Bottle green, green
  • Diaphaneity: Translucent
  • Specific gravity: 4.72
  • Cleavage: {???} Perfect, {010} Good
  • Density: 4.72

Occurrence: Very rare in the oxidized portions of a selenium-bearing Cu–Co deposit.

Congo is the country where Derriksite finds its type and only locality at the Musonoi mine at Kolwezi in the Katanga Copper Crescent. It occurs there in the oxidized selenium-bearing copper-cobalt deposit. Associated minerals include selenian digenite, chalcomenite, demesmaekerite, and malachite.

Association: Selenian digenite, chalcomenite, demesmaekerite, malachite

 

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