MINERALOGY OF THE GROOTE EYLANDT MANGANESE OXIDES: A REVIEW

Abstract

The mineralogy and genesis of the tetravalent manganese oxides present in the Groote Eylandt ore are discussed on the basis of recent mineralogical concepts. Their mechanisms of formation on Groote Eylandt are described in terms of primary sedimentation (formation of vernadite, romanechite, pyrolusite, todorokite); diagenesis (formation of pyrolusite); supergene processes (formation of cryptomelane and lithiophorite) and pedogenic processes (formation of chalcophanite and birnessite). These geochemical processes have resulted in the formation of deposits of metallurgical ore of a cryptomelane-pyrolusite mineralogy and a battery-active ore of vernadite-todorokite-pyrolusite mineralogy.