So, what are minerals then?
According to the International Mineralogical Association “a mineral is an element or chemical compound that is normally crystalline and that has been formed as a result of geological processes.” That definition basically covers everything: rocks, gemstones and even organically derived things like amber, jet and pearls. There are over 4,000 known minerals, but only about 100 of them are common. More than half of the known universe of minerals is so rare that they have been found only as handfuls or very minute specimens. In one system of classification of minerals, there are 9 main classes that all minerals fall into based on their chemical composition. These are Silicates (quartz, garnet); Carbonates (calcites, aragonite, shell fossils); Sulfates (selenite, celestite); Halides (halite, fluorite); Oxides (hematite, ruby); Sulfides (pyrite, copper); Phosphates (Apatite, Turquoise); and Organics (jet, amber).
