Uses of Rocks

Rocks are very important economically. The thin surface layer of the earth, formed by the break-down of the rocks in various ways and by various processes, is known as soil. The geographer is, among other things, interested in the soil as the medium in which plants grow, hence the scene of production of most of man's food and most of his raw materials.
Man's vital water supply is connected with the nature of the rocks. Part of our drinking water is got by sinking wells to tap the sub-surface water which is filtered naturally during its passage through the rocks. The amount of surface run-off in the form of rivers and springs affects the siting of
villages.
Rocks provide building materials. Granite is quarried in many parts of Nigeria for road construction, decking of houses and other building purposes.
Various limestones are burnt to produce lime, for mortar and for agricultural use. Cement is made by burning a mixture of two-thirds limestone or chalk and one-third clay, and grinding the result to fine powder.
Some rocks are important to man as sources of fuel. Lignite, bituminous and steam coals, anthracite and mineral oil (petroleum) are examples of vital sources of fuel.
In various parts of the world there are large deposits of salts. Examples are phosphates in Tunisia and Morocco, and potash at Stassfurt in Germany. Salt is obtained near Kaolack in Senegal and refined in the town.
Of great economic significance is brick which is made from clay.
Gravel is quarried to make concrete for use in the building industry. The commonest types are quartz and laterite gravel.
Rocks are sources of various economic metals. Metals such as gold, coper, tin, lead, zinc and silver, though extremely rare in ordinary rocks, are locally concentrated in ore deposits which can be economically extracted.