Nickel–Strunz classification
Nickel–Strunz classification is a scheme for categorizing minerals based upon their chemical composition, introduced by German mineralogist Karl Hugo Strunz (24 February 1910 – 19 April 2006) in his Mineralogische Tabellen (1941). The 4th and the 5th edition were also edited by Christel Tennyson (1966).
Source: Wikipedia — Nickel–Strunz classification (CC BY-SA 4.0)