ABSTRACT
Geochemical methods of prospecting for 14 genetic types of non-metallic minerals, whose deposits are characterized by independent mineral phases are discussed in this section. Deposits of this group include gems (diamond, topaz, beryl, ruby, sapphire, emerald, garnet, chrysolite, chrysoprase and turquoise); abrasives (diamond, garnet and corundum); piezooptic minerals (rock crystal and Iceland spar), anti-abrasives (agate and chalcedony), as well as mica, asbestos and graphite. The ore of the latter is rock containing minerals with a certain correlation of components (for example, the iron content in fluorphlogopite should not exceed 14 per cent). With the exception of malachite, chrysoprase, and turquoise, the entire group of these deposits relates to endogenic formations. Diamond, garnet, ruby, sapphire, rock crystal, and agate are concentrated also in placers. The majority of these useful minerals are used by industry without violation of their initial integrity. Only asbestos and graphite are subjected to mechanical treatment. Despite the variety of these raw materials, they are characterized by a series of common features:
(1) Useful minerals contain mainly petrogenic elements, that are widespread in the earth's crust: C, Si, Al, Ca, Mg and K (Be is an exception).
