An ore can be described briefly as an accumulation of mineral in sufficient quantity as to be capable of economic extraction.
This establishes the market price of the metal as a critical criterion in the definition, and this will vary according to the commercial demands.
With the passage of time and depletion of richer or more readily accessible material, a mineral deposit may be updated to an ore.
Improvement in metallurgical extraction and the introduction of new methods also become factors in making available deposits hitherto regarded as uneconomic.
Thus the introduction of the flotation process in mineral processing permitted the extraction of copper from material containing less than 0.5% of the metal and formerly regarded as waste, Similarly the introduction of solvent extraction has enabled Nchanga Consolidated Copper Mines in Zambia to treat 9 million tonnes per year of flotation tailings, producing 80,000 tonnes of finished copper from what was previously regarded as waste material.
因此，在矿物加工中引入浮选工艺可以从含铜量少于0.5%的材料中提取铜，以前这些材料被视为废物。同样萃取剂的引入使得赞比亚Nchanga合并铜矿能够每年处理900万吨浮选尾矿，从以前被视为废料的地方生产了80000吨成品铜Ores are frequently classed according to the nature of the valuable mineral.
Thus in native ores the metal is presented in the elementary form; sulphide ores contain the metal in the form of a sulphide, and in oxidised ores the valuable mineral may be present as oxide, sulphate, silicate, carbonate, or some hydrated from of these.
Complex ores are those containing profitable amounts of more than one valuable mineral.
Metallic minerals are often found in certain associations, within which they may occur as mixtures of a wide range of particle sizes or as single-phase solid solutions or compounds.
Galena and sphalerite, for example, commonly associate, as do copper sulphide minerals and sphalerite to a lesser extent. Pyrite (FeS2) is very often associated with these minerals.