Derriksite - Encyclopedia
Class : Oxides et hydroxides
Subclass : Uranyl selenites
Crystal system : Orthorhombic
Chemistry : Cu4(UO2)(SeO3)2(OH)6
Rarity : Very rare
The appearance of derreksite and other uranium selenites requires the joint presence of sufficient quantities of selenium and uranium in the same deposit. These conditions are only met exceptionally, which explains the great rarity of these minerals, only four in number (guilleminite, demesmaekerite, derriksite and marthozite), and their presence in only two deposits. It was named in honor of the Belgian geologist Joseph Derriks who studied the Shinkolobwe uranium deposits in Katanga. Derricksite forms small automorphic crystals not exceeding 0.7 mm, elongated or tabular, green to bottle green in color. Like demesmaekerite and guilleminite, it appears essentially in microcrystalline crusts on a seleniferous digenite which provided the selenium necessary for the formation of uranyl selenites.
Main photo : Derriksite from Musonoi Mine, Kolwezi, Mutshatsha, Lualaba, D.R. Congo © Christophe Boutry
Derriksite in the World
Twinning
No twin known for this mineral species.
Fakes and treatments
No fakes listed for this mineral species.
Hardness : 4
Density : 4.61
Fracture : Undetermined
Streak : Green
TP : Translucent
RI : 1.770 to 1.890
Birefringence : 0.120
Optical character : Biaxial -
Pleochroism : Visible
Fluorescence : None
Solubility : -
Magnetism : None
Radioactivity : Strong