Talnakhite

Talnakhite is a mineral of chalcopyrite group with formula: Cu₉(Fe, Ni)₈S₁₆. It was named after the Talnakh ore deposit, near Norilsk in Western Siberia, Russia where it was discovered as reported in 1963 by I. Budko and E. Kulagov. It was officially named "talnakhite" in 1968. Despite the initial announcement it turned out to be not a face centered high-temperature polymorph of chalcopyrite, but to have composition Cu₁₈(Fe, Ni)₁₈S₃₂. At 80 °C (176 °F) to 100 °C (212 °F) it decomposes to tetragonal cubanite plus bornite.