A rock is an aggregate of minerals in a solid state. On the other hand the term rock can include substances like clays, shells, sandstones and corals. Rocks which contain metallic compounds are called ores. The rock has following importance;-
(1) Rocks are very important in the formation of soils which can be used for agricultural production.
(2) Rocks are used for building purposes: some rocks such as limestone, sandstone, gravels and sand are used for building houses, construction of roads, etc.
(3) Some rocks are used as sources of energy or fuel such as coal and petroleum (mineral oil).
(4) Limestone is widely used for cement manufacturing. In Tanzania, cement is produced at Tanga, Mbeya and Wazo Hill.
(5) Salt extraction: salt usually originate from rock accruing strata, for instance, in Tunisia and Morocco there are large deposits of salt.
(6) Manufacture of chemicals: some rocks contain nitrate or phosphate, while others have potash. This kind of rocks can be used for making dyes, fertilizers and medicines.
(7) Mineral deposits: mineral ores occur in veins of some rocks such as igneous rocks. The minerals are formed when the magma coos down. Valuable minerals extracted from rocks include gold, lead, tin, silver, diamond, copper, zinc, aluminium, calcium and manganese.
(8) Some rocks are so impressive such that they attract tourist to come and view them. In so doing, the country earns a lot of foreign exchange.
(9) Some rocks are used for decoration of houses as ornaments or they are grinded to produce powder which is used for decoration.