Krause, Werner; Kolitsch, Uwe; Bernhardt, Heinz-Jü rgen; Effenberger, Herta
published: Feb 7, 2003
Reinvestigation of duhamelite, originally described as Cu4Pb2Bi(VO4)4 (OH)3 · 8H2O, has demonstrated that it is not a valid independent mineral species. Analyses of the type material and of additional samples by means of electron microprobe, X-ray powder and single-crystal diffractometry including structure refinements, and transmission electron microscopy have shown that duhamelite belongs to the adelite-descloizite-group with the general formula AB(XO4)(OH). Duhamelite in the strict sense corresponds to a bismuth- and calcium-bearing mottramite; the empirical formula of the type material is (Pb0.49Bi0.36Ca0.12)Σ0.97Cu1.01[(VO4)0.85 (AsO4)0.08(SiO4)0.07]Σ1.00[O0.27(OH)0.71]Σ0.98 (based on 5 oxygen atoms per formula unit), or simplified (Pb,Bi,Ca)Cu(VO4)(OH,O). The formal discreditation of duhamelite has been approved by the Commission on New Minerals and Mineral Names, I.M.A.