Gold and Silver Minerals in Sulfide Ore

Abstract

Abstract—Gold and silver are capable of forming stable natural compounds with different elements. For gold 36 minerals are known: 10 in the class “Native metals, intermetallic compounds” and 26 in the class “Sulfides (selenides, tellurides, arsenides, antimonides, bismuthides).” For silver, 194 minerals are registered in the MMA, presented in 8 classes. Compared to gold in the class “Native metals, intermetallic compounds” there are far fewer silver minerals. They are widely represented in the classes “Sulfides” and “Sulfosalts” (124). Among silver minerals “halides” are also known (fluorides, chlorides, bromides, iodides), seven; simple and complex oxides, two; there is one mineral each in the classes “sulfates,” “phosphates,” “arsenates,” and “vanadates.” Both metals are in the compositions of 12 minerals: native gold, native silver, weishanite, uytenbogaardtite, petrovskaite, fishesserite, penzhinite, petzite, mutmannite, sylvanite, krennerite, and bezsmertnovite. Every year, the MMA commission registers four to six gold and silver minerals, so there are prospects for the discovery of new minerals of these precious metals in the near future. The indicator elements (fixers) that form natural compounds with gold and indicate the possible presence of gold minerals in sulfide ores include 13 elements: 7 metals (Ag, Cu, Pd, Hg, Sn, Tl, Fe), 3 chalcogens (Te, S, Se), and 3 metalloids (As, Sb, Bi). For silver, this range is wider and also includes such elements as Mn, Zn, Ge, Cd, V, O, H, F, Cl, Br, I, In, and N. This review presents and summarizes the results of studies on the composition of native gold with copper, mercury, and palladium impurities in different types of gold deposits. The article describes the gold and silver minerals established by the author together with colleagues in a study of productive mineral assemblages in some gold deposits in Russia: the Ulakhan, Yunoe, Krutoe, Dzhulietta, Dorozhnoe (Magadan region), Konechnoe (Taimyr Peninsula), Kupol, Valunistoe (Chukotka), Maletoyvayam (Kamchatka), etc. Data are presented on gold and silver minerals found in sulfide ores and of economic importance. Some of their technological properties are characterized, including solubility and behavior under the influence of various reagents. The presence of refractory minerals (calaverite, sylvanite, krennerite, petzite, aurostibite, maldonite, fishesserite, uytenbogaardtite, petrovskaite, penzhinite, weishanite, yuanjianite, hunchunite, anyuite, krynovite, nadjagite, and bogdanovite, bilibinskite, criddleite, etc.), as well as the chemical composition gold and silver, are important technological factors and should be taken into account when developing a technology for extracting precious metals from ores. The presence of increased concentrations of indicator elements (fixers) of gold and silver minerals in sulfide ores is an important indicator and argument for detailed mineralogical and geochemical studies of the source raw material. Identification of mineral (micro-, nano-) forms of gold and silver in sulfide ores is necessary for developing and improving rational dressing schemes.