The minerals that constitute the earth's crust have been formed from the chemical elements that originated the planet, thanks to reactions that occurred inside.
For this reason, the number of combinations is immense.
To put a little order, minerals are classified according to the way they originate, their crystallographic characteristics, their chemical composition ... Crystals deserve a special mention and, among them, the so-called precious stones that have always captivated humanity.
The chemical classification divides minerals into groups according to their chemical compounds. Any known mineral can be integrated into these groups, since almost all of them include some of these compounds.
1.- Native elements: are those found in nature in a free, pure or native state, without combining or forming chemical compounds. Examples: gold, silver, sulfur, diamond.
2.- Sulphides: compounds of various minerals combined with sulfur. Examples: pyrite, galena, blenda, cinnabar.
3.- Sulfosales: minerals composed of lead, silver and copper combined with sulfur and some other mineral such as arsenic, bismuth or antimony. Examples: pyrargirite, proustite.
4.- Oxides: product of the combination of oxygen with an element. Examples: oligisto, corundum, cassiterite, bauxite.
5.- Halides: compounds of a halogen with another element, such as chlorine, fluorine, iodine or bromine. Examples: common salt, halite.
6.- Carbonates: salts derived from the combination of carbonic acid and a metal. Examples: calcite, azurite, marble, malachite.
7.- Nitrates: salts derived from nitric acid. Examples: sodium nitrate (or from Chile), nitrate or potassium nitrate.
8.- Borates: constituted by mineral salts or esters of boric acid. Examples: borax, rasorite.
9.- Phosphates, arseniates and vanadates: salts or esters of phosphoric acid, arsenic and vanadium. Examples: apatite, turquoise, pyromorphite.
10.- Sulfates: Sulfates are salts or esters of sulfuric acid. Examples: plaster, anhydrite, barite.
11.- Chromatos, volframatos and molibdatos: chromium, molybdenum or tungsten compounds. Examples: wolframita, crocita.
12.- Silicates: salts of silicic acid, the fundamental compounds of the lithosphere, forming 95% of the earth's crust. Examples: silica, feldspar, mica, quartz, pyroxene, talc, clay.
13.- Radioactive minerals: composed of radiation emitting elements. Examples: uraninite, torianite, torita.
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