[xenadu02]

Also remember things are not like the movies. Most gold is not found in large single chunks. It is found as tiny inclusions scattered within a larger piece of rock, sometimes put there by flash deposition deep in the crust (earthquake or whatever lowers pressure, water instantly flashes to steam, dissolved minerals and floating particles fall out).

The same goes for other materials: They are often interspersed with lots of other minerals or the ore form is actually several different compounds in random mixtures.

Another example is Aluminum which comes from Bauxite. We say Bauxite as if it was one single thing but its actually a varying mix of Al(OH)3, AlO(OH), FeO(OH), Fe2O3, Al2Si2O5(OH)4, TiO2, FeTiO3, FeOTiO2, and traces of others. The actual composition varies within and between veins.