silver, chalcopyrite, pyrite, erythrite, skutterudite and other cobalt minerals
Major Occurrences: include cobalt, Ontario, Canada; Zaire; Siegerland, Germany; Skutterud, Norway; Tunaberg, Sweden; Sonora, Mexico; England; Boulder, Colorado and other USA localities
Best Indicators: crystal habit, cleavage, colour, streak, association with erythrite and luster