The chemical diversity of minerals can be analysed in terms of the concept of mineral systems, defined by the set of chemical elements essential for the definition of a mineral species. Only species-defining elements are considered as essential. According to this approach, all minerals are classified into ten types of mineral systems with the number of essential components ranging from 1 to 10. For all the minerals known today, only 70 chemical elements act as essential species-defining constituents. The number of minerals of different chemical elements are calculated as follows (number of mineral species is given in parentheses): oxygen (4138), hydrogen (2814), silicon (1479), calcium (1182), sulfur (1064), aluminum (989), sodium (953), iron (953), copper (643), arsenic (601), phosphorus (599), and magnesium (576). The distribution of the majority of the species-defining elements among mineral systems submits to a normal distribution. Using the concept of mineral systems, different geological objects can be compared from the viewpoint of their mineral diversity as exemplified by alkaline massifs (Khibiny, Lovozero, Russia, and Mont Saint-Hilaire, Canada), evaporite deposits (Inder, Kazakhstan, and Searles Lake, USA) and fumaroles at active volcanoes (Tolbachik, Kamchatka, Russia, and Vulcano, Sicily, Italy). The concept of mineral systems can be applied to mineral evolution overall by calculating the mean number of elements for the first three stages in the evolution of minerals as proposed by R.M. Hazen and co-authors in 2008, plus a fourth period corresponding to Hazen’s stages 4-10, as follows: 2.08 ± 0.45 (I: ur-minerals); 2.68 ± 0.13 (II: minerals of chondritic meteorites); 3.86 ± 0.07 (III: Hadean minerals); 4.50 ± 1.47 (IV: post-Hadean minerals).