Jamesite (w. dolomite, duftite and tsumcorite)

dolomite; duftite; goethite; tsumcorite

A cavernous, goethite-rich matrix of extensively oxidised sulphide ore, richly encrusted with localised concentrations of yellow to orange-yellow tsumcorite, dark blackish-green duftite crystals, snow-white rhombohedral dolomite crystals and red-brown jamesite. This is a particularly rich jamesite specimen with prominent sub-spherical aggregates (to 1 mm) of radially arranged acicular crystals (exhibits 2 and 3). All minerals have been verified by EDS but on other specimens from this paragenesis.

The specimen is in the collection of Sharon and Eugene Cisneros, who acquired it from Walter R. Kahn. It is from the second oxidation zone at Tsumeb and, although there is no formal record of the location in the mine for this particular specimen, the paragenesis is diagnostic for 30 Level, East 49, which was the source of the holotypes for both tsumcorite (Geier et al. 1971) and jamesite (Keller et al. 1981b; see also https://tmn.fas.harvard.edu/objects/TSNB183/ ). This specimen almost certainly originates from the material collected by TCL mineralogist Bruno Geier in 1964 and documented by him several years later (Geier et al. 1971).
 
Compare with TSNB422.