PLACER AND ORE GOLD
PLACER AND ORE GOLD, 1) mineral of the class of native elements, Au; 2) natural mineral formations containing gold in the quantities, which make it economically expedient to be extracted with the help of modern industrial methods. Placer gold is found in the form of natural alloys with silver (up to 43%). Natural isolations weighing more than 5 g are called nuggets. They are concentrated in hydrothermal, sulphide deposits and placers. The largest nugget in Russia Big Triangle weighing 36.2 kg was found in 1842 near the Tashkutargan River at the Tsaryovo Aleksandrovsky Placer Mine. Nugget Irendyksky Bear weighing 4.79 kg was found, in 1992, at Derevnya Kuseyevo of Baymaksky Raion; many nuggets weighing up to 1 kg have been found in the basins of rivers Mindyak and Miass in the Uchalinsky Raion.
According to the geological industrial feature, there are 4 gold ore formations (ore formation types): gold silver, sulfide, quartz, sulfide quartz. Gold ore deposits can be divided into the deposits of gold ore proper and the deposits of complex goldbearing ore: iron copper nickel, pyrite polymetallic, and copper sulphide deposits, where gold is the part of the ores of nonferrous, rare and noble metals; also there are deposits of gold bearing conglomerates, that comprise over 35% of the world’s gold reserves. There are 3 gold ore formations in the territory of the Republic: gold sulfide, gold quartz, gold sulfide quartz. They are located within the Western Ural and Eastern Ural metallogenic provinces. The deposits of the gold sulfide formation are mainly represented by gold bearing zones of stringer porphyry mineralization, localized in the carbonate and terrigenous masses of the Western Ural metallogenic province (Gorny Priisk, Aktash, and Bagryashka deposits in the Avzyansky Ore Raion), in metabasalts and volcanogenic sedimentary Paleozoic masses of the Eastern Ural metallogenic province (Mindyak, Murtykty deposits, etc). Average gold content in ore is 5–7 g/t. The gold quartz formation is developed within the Western Ural metallogenic province (the deposits and manifestations of Kalashnikova Zhila, Sudovaya Polyana, etc); the deposits of this formation are small. The deposits of the gold sulfidequartz formation are common (VasilyeNikolayevskoye, Staro Timofeyevskoye, etc in the Uchalinsky Ore Raion, manifestations of the western flank of the Khudolazovskaya Syncline and Gadelshinskoye in the Baymaksky Ore Raion). They include the deposits in the rocks of the Yarlykapovo horizon of the Eifelian strata in the Abzelilovsky and Baymaksky ore raions, forming a single Irendyk Ore Zone (Allagul Tau, Ishberdinskoye, Malo Yarlykapovskoye deposits, etc).
The mineralization of the gold limestonesilicate subformation, represented by minor manifestations of copper magnetite goldbearing ores in serpentinite (Urgunovskoe Deposit), is observed in the Uchalinsky Ore Raion, as well as the veins associated with ultrabasic and basic rocks of the ophyolitic belt of the Urals. The mineralization of gold and platinum was established in the volcanogenic sedimentary rocks of the Mashak Suite (Avzyansky Ore Raion).
