Occurrence of Copper Bearing Chalcophanite from Gottivada Manganese Ores, Eastern Ghats, Andhra Pradesh

Chalcophanite (Zn, Cu) Mn₃0₇.3H₂0 is reported from Gottivada Manganese Ores (17°32'O"N - 82°44'50" E). The mineral crystallises in the triclinic system with a=7.5201; b=7.5102, c=8.1324 Å; α=90°, β=116°40',γ=120° space group P1. The structure of chalcophanlte is characterised by single sheets of water molecules grouped in open double hexagon rings alternating with double oxygen layers. The seventh octahedral site in the structure is occupied by Mn, Zn and Cu atoms linked to the triads of oxygens. Bonding of the vacanies in the Mn layer complete the octahedral co-ordination with the triads of water molecules. Physical, optical and chemical properties of copper bearing chalcophanite are described in detail. The chalcophanite is a secondary colloform manganese mineral formed from the gels that contains copper and zinc atoms with manganese hydrolizates.