Metallurgy

Naturally occurring chemical substance in earth crust obtained by mining.

Mineral from which metal can be extracted conveniently and economically.

Rocky or earthy impurities associated with ore.

Metals in free state; Ag, Au, Pt.

Oxides or oxysalts such as carbonates, phosphates, sulphates and silicates.

Sulphides of metals such as Fe, Pb, Zn and Hg.

Halides of metals.