A mineral is a naturally occurring, inorganic solid with a definite atomic structure and chemical composition. An element must meet the following five conditions to be defined a mineral: naturally occurring, solid, definite chemical composition, inorganic, and definite internal structure.
A naturally occurring substance cannot be directly produced or altered by human activity. An element such as steel is not considered a mineral because it is an alloy. Solid means that the element does not exist as gas or liquid at its natural state and under the standard pressure and temperature. A definite chemical composition means that the naturally occurring element has a specific chemical signature that distinguishes it from other elements. An inorganic substance is not produced by organisms, substances such as pearls and wood are organic because they are produced by activities of living organisms. An element with a definite internal structure means that the atoms are arranged predictably.
The fundamental physical properties of minerals include hardness, tenacity, specific gravity, cleavage, magnetism, electrical conductivity, and reaction to acids. The physical properties of minerals alongside optical properties such as the refractive index, luster, light and the absorption of specific light rays allow minerals to be positively identified and distinguished by instruments.
Formation of Minerals
Minerals are formed in various geologic environments including salt lakes, volcanoes, deep oceans, and molten rocks. Minerals can also be formed by exposing certain elements to extreme temperature and/or pressure, or by combining solutions and gases with certain concentration of specific elements. Extreme temperature and pressure alter the existing chemical composition of the elements and introduce the elements that are in the solution or gases. The suitable environment allows crystallization to occur leading to the formation of minerals
Difference Between Minerals and Rocks
A mineral is a naturally occurring, inorganic solid with a definite atomic structure and chemical composition. A rock is an aggregation of one or several particles of minerals. One mineral can aggregates to form rocks such as quartzite while several minerals can aggregate to form rocks such as granite. Igneous rocks are formed by the crystallization of molten magma. When minerals settle and experience immense pressure, they form sedimentary rocks. When minerals are reheated and subjected to high pressure alongside pre-existing rocks, they form metamorphic rocks. Rocks do not have definite atomic structure of chemical composition.
Some minerals are easily recognizable because of their distinctive shape and color, but some require nondestructive test to ascertain their identity. Simple tests include determining the refractive index, color, transparency, melting point, magnetism, specific gravity, radioactivity, and chemical tests. In some cases, tests involve more complex instruments such as X-ray diffractometers, energy dispersive spectrometer, and the electron microprobe.