Composition: Cu2+4(SO4)(OH)6.H2O
Crystal System : Monoclinic
Colours: Intense blue
Lustre : Vitreous
Hardness (H) : 2.0-3.0
Specific Gravity (S.G) : 3.32


Very rare. First oxidation zone. Second oxidation zone (?)


  • Supergene
  • 1st Oxidation Zone
  • 2nd Oxidation Zone

Paragenetic and General Notes

Posnjakite forms crystals (<1 mm) and crusts on tennantite pseudomorphs after enargite. It is also observed on cerussite and on oxidised surfaces of sulphide material.