For which of the following ores calcination process cannot be used?
ZnS
Calcination is the process of conversion of metal carbonates and metal oxides to metals by heating the ores in the limited supply of air. Sphalerite ((Zn, Fe)S) is a mineral that is the chief ore of zinc. It consists largely of zinc sulfide in crystalline form but almost always contains variable iron.
Hence, from the options, ZnS (zinc sulfide) is the only ore that can't be extracted by calcination.