What are ores made up of?
Ores are made up of economically valuable minerals mixed with non-valuable rock or gangue minerals. For example, gold ore is often mostly quartz with a small amount of gold. The quartz is gangue, and the gold is the ore mineral. Minerals are naturally-occurring chemical compounds that have a definite crystal structure. When ore is processed, the valuable minerals are removed from the ore, and then may be further processed. Usually, an ore is processed to extract a particular element, often a metal. For example, copper ore might consist of chalcopyrite, CuFeS2, mixed with rock. The chalcopyrite could be concentrated by froth flotation (producing rock tailings as waste) and then smelted to produce copper metal (along with sulfur dioxide and iron oxide as byproducts). In other cases, the mineral is used as the same chemical compound – one can speak of asbestos ore or diamond ore – the mineral is separated from the gangue and then used as is.
