Derriksite , Malachite Locality: Musonoi Mine, Kolwezi , Western area, Katanga Copper Crescent, Katanga (Shaba) , Democratic Republic of Congo (Zaïre) ( Locality at mindat.org ) Size: 8.5 x 4 x 4.5 cm. Good sized crystals of the very rare copper-uranium-selenite Derriksite on a bed of Malachite. The mineral occurs rarely as good visible, bottle green crystals. The matrix is selenium-rich Digenite. This specimen was recovered when the uranium dump of Musonoi was sent to the Kolwezi concentrator in the early 1990’s. Musonoi is the type and only known locality for Derriksite where it is known as the rarest of the selenites. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Derriksite
A very rare bright-green copper-uranium selenite — a secondary mineral combining copper, uranium and selenium.
Intro adapted from Wikipedia (CC BY-SA).
Derriksite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Cu₄(UO₂)(Se⁴⁺O₃)₂(OH)₆.
It crystallizes in the orthorhombic crystal system (space group Pn2_1m).
Key properties: specific gravity 4.61; optically biaxial.
IMA symbol Drk, IMA status: approved, named in 1971.
Very rare in the oxidized portions of a selenium-bearing Cu–Co deposit.
It is found associated with Selenian digenite, chalcomenite, demesmaekerite, malachite.
The mineral was named to honor Jean Marie François Joseph Derriks (1912–1993), Belgian geologist who studied the Shinkolobwe uranium deposit.