Most metals are found in nature in a combined state, owing to their high reactivity. Metals found in a combined state in the earth's crust are known as minerals. Only those minerals that have a relatively high concentration of metal and can be extracted in an easy and cost-effective process are called ores.
The only metals found in free (or) native state are gold and platinum. They are usually found along with earthly (or) rocky impurities such as sand and clay in the earth's crust.
The relative abundance of metals varies in the earth's crust.
Relative abundance of some of the metals in the earth's crust by weight:
| Metal | Relative Abundance by Weight % |
| Al Fe Ca Na Mg K Ti |
8.23 5.80 4.15 2.36 2.23 2.09 0.46 |
Aluminium and Iron are relatively more abundant than others. Aluminium constitutes about 8%, while iron constitutes 5.8 % by weight of the earth's crust.
Thus, aluminium is the most abundant metal and Iron the second most abundant metal by weight in the earth's crust. Also, aluminium is the 3rd most abundant element and Iron the 4th most abundant element by weight of the earth's crust.
The principal ores of some important metals, and their composition:
| Metal | Ores | Composition |
| Aluminium (Al) | Bauxite, kaolinite (A Form of Clay) |
AlOx(OH)3-2x [Where 0<x<1] Al2(OH)4Si2O5 |
| Iron (Fe) | Haematite Magnetite Siderite Iron pyrites |
Fe2O3 Fe3O4 FeCO3 FeS2 |
| Copper (Cu) | Copper pyrites Malachite Cuprite Copper glance |
CuFeS2 CuCO3.Cu(OH)2 Cu2O Cu2S |
| Zinc (Zn) | Zinc blende or Sphalerite Calamine Zincite |
ZnS ZnCO3 ZnO |
Both aluminium and iron are used widely in industrialised nations. Naturally occurring aluminium is a major component of silicates such as mica and clay. Aluminium is extracted mainly from its principal ore bauxite.
Valuable gem stones such as rubies and sapphires contain aluminium oxides along with traces of transition metals as impurities. Rubies are crystalline forms of aluminium oxide, which are red in colour due to the presence of chromium as an impurity. Sapphires are available in various shades owing to the presence of impurities such as nickel, cobalt and titanium.
Iron is mainly extracted from its oxide ores such as haematite and magnetite. The iron extracted from these ores is mostly used in the manufacture of steel an alloy of iron. Iron is also an essential element found in biological systems.
Other metals that are extensively used are copper and zinc.
Summary
Most metals are found in nature in a combined state, owing to their high reactivity. Metals found in a combined state in the earth's crust are known as minerals. Only those minerals that have a relatively high concentration of metal and can be extracted in an easy and cost-effective process are called ores.
The only metals found in free (or) native state are gold and platinum. They are usually found along with earthly (or) rocky impurities such as sand and clay in the earth's crust.
The relative abundance of metals varies in the earth's crust.
Relative abundance of some of the metals in the earth's crust by weight:
| Metal | Relative Abundance by Weight % |
| Al Fe Ca Na Mg K Ti |
8.23 5.80 4.15 2.36 2.23 2.09 0.46 |
Aluminium and Iron are relatively more abundant than others. Aluminium constitutes about 8%, while iron constitutes 5.8 % by weight of the earth's crust.
Thus, aluminium is the most abundant metal and Iron the second most abundant metal by weight in the earth's crust. Also, aluminium is the 3rd most abundant element and Iron the 4th most abundant element by weight of the earth's crust.
The principal ores of some important metals, and their composition:
| Metal | Ores | Composition |
| Aluminium (Al) | Bauxite, kaolinite (A Form of Clay) |
AlOx(OH)3-2x [Where 0<x<1] Al2(OH)4Si2O5 |
| Iron (Fe) | Haematite Magnetite Siderite Iron pyrites |
Fe2O3 Fe3O4 FeCO3 FeS2 |
| Copper (Cu) | Copper pyrites Malachite Cuprite Copper glance |
CuFeS2 CuCO3.Cu(OH)2 Cu2O Cu2S |
| Zinc (Zn) | Zinc blende or Sphalerite Calamine Zincite |
ZnS ZnCO3 ZnO |
Both aluminium and iron are used widely in industrialised nations. Naturally occurring aluminium is a major component of silicates such as mica and clay. Aluminium is extracted mainly from its principal ore bauxite.
Valuable gem stones such as rubies and sapphires contain aluminium oxides along with traces of transition metals as impurities. Rubies are crystalline forms of aluminium oxide, which are red in colour due to the presence of chromium as an impurity. Sapphires are available in various shades owing to the presence of impurities such as nickel, cobalt and titanium.
Iron is mainly extracted from its oxide ores such as haematite and magnetite. The iron extracted from these ores is mostly used in the manufacture of steel an alloy of iron. Iron is also an essential element found in biological systems.
Other metals that are extensively used are copper and zinc.