With oxidation states: Cu1+6Cu2+2(S2-)5 (CM 23.61-76)
Sulphide, chalcocite group
Specific gravity: 5.61 calculated
Hardness: 3½ to 4
Colour: Bluish-white, may be iridescent
Common impurities: Fe,Zn
Geerite occurs in serpentine hosted
associated with andradite,
and spionkopite. Geerite may be partly or completely
replaced by spionkopite
At Eretria, Euboea, Central Greece, Greece, geerite occurs in a serpentine hosted chromite-magnetite deposit associated with spionkopite, chalcopyrite, cobaltpentlandite, magnetite, chromite, andradite, chlorite and diopside (HOM).
At the type locality, the geerite locality, De Kalb Township, St. Lawrence county, New York, USA, geerite occurs as a thin, iridescent coating or as platelets up to approximately 15 microns thick. In some specimens geerite is partly or completely replaced by spionkopite. Other associated minerals include sphalerite, tetrahedrite, chalcopyrite, malachite, azurite, brochantite, chrysocolla, cervantite, stibiconite, hemimorphite and calcite (CM 18.519-523).
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