Minerals are naturally occurring inorganic material that have definite structure, composition and properties. Primary minerals are those which originate in the parent rock, e.g. feldspars, pyroxenes, amphiboles, mica, etc.
Secondary minerals are formed from the alteration and decomposition of primary minerals (also called clay minerals since the chief constituent in them is clay), e.g. silicate clays like kaolinite, smectite, vermiculite.
Naturally occurring homogeneous solid having a definite chemical composition as well as a highly ordered atomic arrangement are naturally formed mineral rocks. Mostly they are formed by inorganic processes. There are more than several thousand mineral species, from them about 100 constitute the major mineral components of rocks which are called rock-forming minerals. A mineral is that by definition which must be formed through natural processes and is distinct from the synthetic equivalents being produced in the laboratory. Man-made minerals include, emeralds, sapphires, diamonds, and other valuable gemstones.
Minerals are formed in all geologic environments and also under a wide range of chemical and physical conditions, like temperature and pressure. The four main categories of mineral formation are:
- Igneous - in which minerals crystallize from a melt
- Sedimentary - in which minerals result from the processes of weathering, erosion, and sedimentation
- Metamorphic - in which new minerals form at the expense of earlier ones owing to the effects of changing temperature or pressure.
- Hydrothermal - in which minerals get chemically precipitated from hot solutions inside the Earth.
