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Metals and their compounds are found in earth as natural elements known as minerals. Ores are minerals from which metals are extracted profitably and conveniently. Ores contain metal compounds with a lower percentage of impurities. All the ores are minerals, but all minerals are not necessarily ores.
Types of Ores
| Zincite
(ZnO)
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Marble or limestone (CaCO3)
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Fluorspar
(CaF2)
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Zinc blende (ZnS)
Galena
(PbS)
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Anglesite
(PbSO4)
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| Haematite (Fe2O3.xH2O)Magnetite (Fe3O4)
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Calamine (ZnCO3)
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Cryolite (Na3AlF6)
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Iron pyrites (FeS2)
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Baryl
(BaSO4)
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| Bauxite (Al2O3.2H2O)
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Siderite
(FeCO3)
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Horn Silver (AgCl)
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Cinnabar
(HgS)
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Gypsum (CaSO4.2H2O)
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| Cuprite (Cu2O)
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Magnesite (MgCO3)
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Rock salt
(NaCl)
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Epsom salt (MgSO4.7H2O)
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In the Free State
Very few metals exist in the free or native state. Only metals like gold, platinum and mercury are occasionally found in the free state i.e., in the pure form. Sometimes, copper and silver may also be found in the free state. Such metals are not acted upon by air or water.
In the Combined State
The rest of the metals occur in the combined form as compounds such as oxides, carbonates, sulphides, sulphates, silicates, chlorides, nitrates, phosphates etc. Copper and silver are two metals which occur in free as well as combined state as sulphide, oxide or halide ores. Metals at the top of the activity series (K, Na, Ca, Mg and Al) are so reactive that they are never found in nature as free elements. The metals in the middle of the activity series (Zn, Fe, Pb, etc.) are moderately reactive. They are found in the earth's crust mainly as oxides, sulphides or carbonates.
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