If a mineral-deposit is of sufficient concentration to be profitably worked, it is called an ore deposit.
An ore is a term applied to that part of a metalliferous mineral deposit, which can be used for profitable extraction of one or more metals. The economic mineral of an ore is called ‘ore- minerals’.
The term is used to indicate the useless material associated with ore-minerals. The usual gangue minerals are quartz and other forms of silica, calcite, dolomite, siderite, barite, feldspars, garnet, chlorite, fluorite, apatite, pyrite etc. and sometimes the gangue material is the country-rock itself in which the ore minerals occur.
The metal content of an ore is called the tenor of the ore. It is generally expressed in percentage of the metal.