(i) The term ore is used to describe an accumulation of any mineral mixed with other elements. Minerals are usually found in ores. Metals are extracted from the ores after removing the impurities. Iron ore, bauxite (ore of aluminium), copper ore are examples of ores, from which iron, aluminium and copper are derived respectively. (ii) Certain minerals may occur as alluvial deposits in sands of valley floors and base of hills. These deposits are called ‘placer deposits’. They generally contain minerals which are not corroded by water. Gold, silver, tin and platinum are examples of some important minerals found in ‘placer deposits’