Minerals we call elements occurring in nature and their compounds formed without human participation. All minerals are characterized by a certain, generally constant within certain limits, chemical composition and specific physical properties. The first attempts to classify minerals, when the number of known elements was small and when almost nothing was known about the chemical composition of the minerals, they were based solely on their external appearance, especially on the color. This mainly concerned the classification of gemstones in various medieval and later treatises. Some progress was made with attempts at classification based on other properties besides color, like hardness, form of crystals, cleavage (or lack thereof) e.t.c. However, only a more detailed knowledge of a greater number of elements and the chemical properties of minerals made it possible to create a classification based on. We owe it to the outstanding Swedish chemist J.. Berzeliusowi, which in 1819 r. published the New System of Mineralogy. In the last decades, the classification of minerals has also taken into account their internal structure.
Symbols and names of chemical elements
The basic classes of minerals make up:
1. Elements in the free state, that is, native elements.
2. Sulphides (simple and complex) and analogous metal compounds with selenium, A happier, arsenem i bismuth, i.e.. selenki, tellurki. arsenki i bismuthi.
3. Halides (haloidy), being combinations of metals with chlorine, bromem, jodem i fluorem, i.e.. chlorides, bromki, iodides and fluorides.
4. Oxides and hydroxides.
5. Salts of oxygen acids:
a) nitrates, carbonates, borany,
b) sulfur, chromiany, molybdates, wolframiany,
c) phosphates, arsenates, wanadany,
d) silicates and aluminosilicates (it is the most abundant class of minerals, which was divided into 7 groups based on their internal structure),
e) other salts of oxygen acids.
6. Organic and related compounds.
Gems, being minerals with a very diverse chemical composition, they do not form a separate mineralogical group. In the systematics of minerals based on chemical properties, they belong to different classes. For example, diamond is a native element, rubin, sapphire, spinele, quartz - for oxides, malachite and azurite - to carbonates, turquoise - for phosphates, emerald, akwamaryn, topaz, zircon et al. - to the class of silicates. Also, the physical properties of gemstones do not differ significantly from those of other minerals. Precious stones are formed in nature together with other minerals; however, they rarely form larger aggregates of a deposit nature. For this reason, the issue of the formation of precious stones is closely related to the formation of other minerals.