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

Abstract

Verbeekite, ideally PdSe 2 , monoclinic with space-group choices C2/m, C2 or Cm; a = 6.659 (7) (50)(112). 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 Ag 2 Pd 3 Se 4 , oosterboschite(?), unnamed Pd 2 HgSe 3 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 VHN 5 ranges 490À610, mean 550 kp/mm 2 (2 indentations), roughly approximating a Mohs' hardness of 5Ý. D calc. = 7.211 g/cm 3 for the ideal formula. Electron-microprobe analyses (mean of 4 spot analyses) yielded Pd 39.6, Cu 0.5, Se 58.8, total 98.9 wt.%. The empirical formula is (Pd 0.99 Cu 0.02 ) S1.01 Se 1.99 , based on Pd+Cu+Se = 3. In planepolarized reflected light, the mineral is a nondescript grey and is neither pleochroic nor perceptibly bireflectant. Anisotropy is moderate with rotation tints in varying shades of brown. Reflectance spectra and colour values are tabulated. The name honours Dr Théodore Verbeek (1927À1991) who was the first geoscientist to study the Musonoi palladium mineralization in the Democratic Republic of Congo (1955À1967) and who co-discovered this new mineral phase.

TISCHENDORFITE, Pd8Hg3Se9, A NEW MINERAL SPECIES FROM TILKERODE, HARZ MOUNTAINS, GERMANY

“…The reflectance curves in air and in oil are given in Figure 2. These data are significantly different from those for chrisstanleyite and the other known palladium selenides, oosterboschite (Pd,Cu) 7 Se 5 of Johan et al (1970), palladseite Pd 17 Se 15 of Davis et al (1977), and verbeekite PdSe 2 of Roberts et al (2002).…”

Platinum enrichment at low temperatures and related microstructures, with examples of hongshiite (PtCu) and empirical ‘Pt2HgSe3’ from Itabira, Minas Gerais, Brazil

“…The Pt–Hg selenide has 37–38 wt% Pt, about 26 wt% Hg and 31–32 wt% Se, with 5–7 wt% Pd and up to 1 wt% Cu, yielding (Pt,Pd,Cu) 2 HgSe 3 , or simply Pt 2 HgSe 3 (Table 1). This selenide is stoichiometrically analogous to the unnamed Pd 2 HgSe 3 described in association with other Pd selenides formed at temperatures up to 120°C at Hope’s Nose, Devon, UK (Roberts et al. , 2002).…”

Two‐Dimensional Noble‐Metal Chalcogenides and Phosphochalcogenides

“…: At a temperature of 1600 K and a pressure of 11.5 GPa, 2 O ‐PdSe 2 undergoes a phase transition to the verbeekite structure (Figures f and c) . Verbeekite‐PdSe 2 was first found as a mineral and appears to be a stable polymorph of PdSe 2 (Δ E ≈1.4 kJ mol −1 ), which is closer to the structure of PdP 2 (Figure i) . Lei et al .…”