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Facts about Minerals for Kids


  • A mineral is a naturally occurring substance, representable by a chemical formula, that is usually solid and inorganic, and has a crystal structure.
  • It is different from a rock, which can be an aggregate of minerals or non-minerals and does not have a specific chemical composition.
  • There are over 5,300 known mineral species; over 5,070 of these have been approved by the International Mineralogical Association (IMA).
  • The diversity and abundance of mineral species is controlled by the Earth’s chemistry.
  • Silicon and oxygen constitute approximately 75% of the Earth’s crust, which translates directly into the predominance of silicate minerals.
  • Differences in chemical composition and crystal structure distinguish various species, and these properties in turn are influenced by the mineral’s geological environment of formation.
  • Changes in the temperature, pressure, or bulk composition of a rock mass cause changes in its minerals.
  • Minerals can be described by various physical properties which relate to their chemical structure and composition.
  • Minerals are classified by key chemical constituents; the two dominant systems are the Dana classification and the Strunz classification.
  • All silicate minerals have a base unit of a [SiO4] silica tetrahedra—that is, a silicon cation coordinated by four oxygen anions, which gives the shape of a tetrahedron.
  • Modern advances have included extensive study of liquid crystals, which also extensively involve mineralogy.
  • Many mineral groups and species are composed of a solid solution; pure substances are not usually found because of contamination or chemical substitution.
  • Skinner expanded the previous definition of a mineral to classify “element or compound, amorphous or crystalline, formed through biogeochemical processes,” as a mineral.
  • Overall, around 150 minerals are considered particularly important, whether in terms of their abundance or aesthetic value in terms of collecting.
  • A mineral’s hardness is not necessarily constant for all sides, which is a function of its structure; crystallographic weakness renders some directions softer than others.
  • Cleavage is not a universal property among minerals; for example, quartz, consisting of extensively interconnected silica tetrahedra, does not have a crystallographic weakness which would allow it to cleave.
  • Two-directional cleavage is described as prismatic, and occurs in minerals such as the amphiboles and pyroxenes.
  • Rock forming minerals — typically silicates or occasionally carbonates — have a specific gravity of 2.5–3.5.
  • The degree of polymerization can be described by both the structure formed and how many tetrahedral corners (or coordinating oxygens) are shared.