Text “Mineral deposits”.

Scientific discipline concerned with the distribution of mineral deposits, the economic considerations involved in their recovery, and assessment of the reserves available is called economic geology. Economic geology deals with metal ores, fossil fuels, and other materials of commercial value, such as salt, gypsum, and building stone. Minerals that make up the rocks are defined as inorganic substances which occur naturally and have a definite chemical composition and physical properties which vary within known limits.

The major properties which are used for identification purposes are: colour; crystal form, where available, although most minerals do not show well-developed crystals; cleavage which is the property of minerals to spit along one or more series of parallel planes; specific gravity; hardness which refers to the ability of minerals to scratch or to be scratched; luster which is described in such terms as metallic, glassy, etc. Of these diagnostic properties, colour is, perhaps, the least useful. Cleavage, on the other hand, is one of the most diagnostically useful mineralogical properties that are repeated throughout the mineral.

Minerals of use to man can be grouped into two broad categories according to their physical characteristics: metals, such as aluminium, copper, gold, silver, iron, tin, platinum, chromium, nickel, lead, zinc and non-metals such as diamonds, salt, limestone, cement, sulphur, and asbestos. When minerals occur so that they can be worked as a profit they are called ore deposits.

Economic minerals are those which are of economic importance and include both metallic (ore minerals) and non-metallic, as cryolite and sulphur. The principal reasons for distinguishing non-metallic deposits from metallic are practical ones and include such economic considerations as methods of recovery and uses.