digenite

Digenite is one of a group of copper sulphide minerals of broadly similar physical properties but slightly different stoichiometry. At Tsumeb, chalcocite, digenite and djurleite are the most abundant of these species while roxbyite (Blass et al. 2009) and possibly anilite (Hughes 1987) occur in subordinate quantities. Digenite (like djurleite) typically occurs as lamellar intergrowths with chalcocite.

Schneiderhöhn (1929) considered digenite to be the youngest hypogene mineral at Tsumeb. Sclar and Geier (1957), however, considered it to pre-date galena.

Klein (1938) noted the occurrence of "blauer chalkosin" [= blue chalcocite (an obsolete name for digenite)], between 420 and 460 meters (levels 15 and 16).

Pinch and Wilson (1977) suggested that digenite occurs as small crystals associated with chalcocite.

Hughes (1987) identified digenite as a major component of the sulphide assemblage at Tsumeb and considered most of it (along with most of the chalcocite and djurleite) to be of supergene origin. His evidence for this was the scarcity of deformation textures in the sulphide (refer to Chalcocite section).

Hughes’ (1987) microprobe analysis of digenite from the South 95 Stope on the 29/30 Sill Level returned a composition of 78.2 wt% Cu; 23.5 wt% S and 0.1 wt% Fe.

anilite (?); bornite; calvertite; chalcocite; chalcopyrite; covellite; djurleite; galena; gallite; germanite; pyrite; renierite; roxbyite; silver; wurtzite