Extremely rare. Questionable status at Tsumeb.
Paragenetic and General Notes
Gebhard (1999) notes that a single specimen of calcite with a 20 mm crystal of platy, bronze pyrrhotite is known. However, the mineral does not appear to be listed in any of the (many) ore microscopy studies published in the 1950s, 60s and 70s.
Von Bezing et al. (2014) consider the occurrence of pyrrotite at Tsumeb as questionable.