500 MINERALS/Definition and Classification Mineral Names The author(s) of the original description of a valid new mineral have the prerogative of naming the mineral However, the name must be approved by the CNMMN prior to publication Mineral names have various derivations, the principal ones being the geographical locality of the discovery, a particular characteristic of the mineral, and the name of a person Such names are sometimes called ‘‘trivial’’ to distinguish them from systematic ones In an effort to reduce the proliferation of trivial names, the CNMMN has approved the use of root names with suffixes Suffixed mineral names were introduced by AA Levinson in 1966 for rare-earth minerals, and involves the addition of a hyphenated chemical symbol in brackets after the root name, e.g., synchysite-(Ce) Such suffixes are generally referred to as Levinson modifiers, and the nomenclature of all minerals with one or more rare-earth elements predominating in a structural site must conform to this usage The system of Levinson modifiers has subsequently been extended to some other mineral groups, notably the zeolites Mineral Varieties and Varietal Names In addition to valid mineral names, which apply to mineral species or groups, other names are commonly used for particular varieties of minerals, generally those with distinctive coloring This practice is especially common in gemology Deeply coloured varieties of corundum, for example, have been given varietal names such as ruby (red) and sapphire (blue) Such names have no validity as species names, and their use is not controlled by the CNMMN Mineraloids Mineraloids are substances that have some of the properties of minerals, but are not regarded as valid minerals, usually because they have not been formed exclusively by geological processes One class of mineraloids is those produced by biological processes, such as mineral-like calculi in animals or organic crystals in plants A pearl is therefore classified as a mineraloid rather than as a mineral Some biogenic substances are subsequently found to be formed by geological processes as well, such as the urinary calculi whewellite and weddellite, and these then qualify as mineral species Another class of mineraloids includes synthetic substances Even though they may have a definite chemical composition and a known crystal structure, they not qualify as minerals because geological processes have not been involved in their creation Such substances are called anthropogenic Substances that are formed by a combination of anthropogenic and geological processes are also classified as mineraloids These include substances formed as a result of mine or waste-dump fires and by the action of water on man-made substances In the past, such substances were accepted as mineral species, as, for example, the submerged ancient Laurium slag ‘minerals’, but in recent years the CNMMN has enunciated a policy of not accepting occurrences of such substances as minerals Mineral Classification Historical Background The ancient classification of minerals was based mainly on their practical uses, minerals being classified as gemstones, pigments, ores, etc Probably the earliest classification based on external characteristics and on some physical properties, such as colour, fusibility, malleability, and fracture, was that of Geber (Jabir Ibn Hayyaan, 721–803), later extended by Avicenna (Ibn Sina, 980–1037), Agricola (1494– 1555), and AG Werner (1749–1817) This system was substantially refined by F Mohs (1773–1839) in his Natural-History System of Mineralogy (1820) With Werner, physical classification attained its maturity, and was in general use, by the end of the eighteenth century Linnaeus (1707–78) attempted to classify minerals primarily by their external morphology, with a hierarchical system involving subdivision into genus, order, and class A purely chemical classification was proposed by T Bergmann (1735–84), but this approach was premature, because many chemical elements had not been discovered at that time and analytical procedures were in their infancy AF Cronstedt (1722–65) seems to have been the first to devise a classification scheme involving both chemical and physical properties, with chemistry predominating Systematic crystallography was initiated by JBLR de l’Isle (1736–90), and this concept was applied by RJ Hauă y (17431822) in Traite´ de Mine´ralogie (1801), in which he presented a mineral classification scheme based on the ‘nature of metals’, or, as it would be expressed now, the nature of cations With advances in chemistry, chemical properties became increasingly important, and a chemical classification of minerals was proposed in 1819 by JJ Berzelius (1779–1848) He recognized that minerals with the same non-metal (anion or anionic group) have similar chemical properties and resemble each other far more than minerals with a common metal He considered minerals as salts of anions and anionic complexes, namely, as chlorides, sulphates,