(a) (i) Minerals – The natural materials in which the metals or their compounds are found in earth are called minerals.
(ii) Ores – Those minerals from which the metals can be extracted conveniently and profitably are called ores.
(iii) Gangue – The unwanted impurities like sand, rocky material, earthy particles etc., present in an ore are called gangue.
(b) Before extracting metal from an ore, it is necessary to remove these impurities (gangue) from it. By removing the gangue, we get a concentrated ore containing a much higher percentage of metal. This is called concentration of ore; also known as enrichment of ore.
(c) Ore: Copper glance; Copper (I) sulphide, Cu 2 S.
