Verbeekite, monoclinic PdSe2, a new mineral from the Musonoi Cu-Co-Mn-U mine, near Kolwezi, Shaba Province, Democratic Republic of Congo

Verbeekite, ideally PdSe2, monoclinic with space-group choices C2/m, C2 or Cm; a = 6.659(7), b = 4.124(5), c = 4.438(6) Å, ß = 92.76(3)8, V = 121.7(4) Å3; a:b:c = 1.6147:1:1.0761, Z = 2, is a new, very rare, primary mineral, intimately associated with secondary oosterboschite [(Pd,Cu)7Se5], from the Musonoi Cu-Co-Mn-U mine, near Kolwezi, Shaba Province, Democratic Republic of Congo. Additional associated minerals are Cu- and Pd-bearing trogtalite [(Co,Cu,Pd)Se2], Se-bearing digenite and Se-bearing covellite. The strongest five lines of the X-ray powder-diffraction pattern [d in A ̊ (I) (hkl)] are: 4.423(30)(001), 3.496 (30)(110), 2.718(100)(111), 1.955(50)(310) and 1.896(50)(1̄12). The mineral has also been identified, as a single anhedral 25 mm-sized grain, from Hope’s Nose, Torquay, Devon, England where it is associated with native gold, chrisstanleyite Ag2Pd3Se4, oosterboschite(?), unnamed Pd2HgSe3 and cerussite. At Musonoi, altered verbeekite grains do not exceed 200 mm in size and are anhedral, black, with a black streak and a metallic lustre. The mineral is opaque, brittle, has an uneven fracture, and lacks discernible cleavage. The VHN5 ranges 490610, mean 550 kp/mm2 (2 indentations), roughly approximating a Mohs ’ hardness of 5N. Dcalc. = 7.211 g/cm 3 for the idea