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Ore-genesis theories generally involve three components: source, transport or conduit, and trap. (This also applies to the petroleum industry: petroleum geologists originated this analysis.) Source is required because metal must come from somewhere, and be liberated by some process.
On Earth, there were three eras of mineral evolution. The birth of the Sun and formation of asteroids and planets increased the number of minerals to about 250. Repeated reworking of the crust and mantle through processes such as partial melting and plate tectonics increased the total to about 1500.
Gold, a chemical element; Genomes OnLine Database; Global-scale Observations of the Limb and Disk, a NASA Explorer Mission of Opportunity; GOLD (parser), an open-source parser-generator of BNF-based grammars; Graduates of the Last Decade, an Institute of Electrical and Electronics Engineers program to garner more university level student members
Gold cycling starts with the microbial weathering of gold-bearing rocks and minerals which mobilizes gold in the environment via release of elemental gold and solubilization. [ 2 ] [ 3 ] The Witwatersrand gold deposits host approximately 30% of the world's gold resources, a large proportion of which is directly associated with organic carbon ...
Orogenic gold deposits are responsible for approximately 75% of the world's gold production at over 1 billion ounces, when accounting that the origin of many gold placer deposits were orogenic in nature. [25] [46] The price of gold at a given time will have an impact on whether a deposit will be economically feasible.
Gold occurs principally as a native metal, i.e., gold itself.Sometimes it is alloyed to a greater or lesser extent with silver, which is called electrum.Native gold can occur as sizeable nuggets, as fine grains or flakes in alluvial deposits, or as grains or microscopic particles (known as colour) embedded in rock minerals.
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A miner underground at Pumsaint gold mine, Wales; c. 1938 Landscape of Las Médulas, Spain, the result of hydraulic mining on a vast scale by the Ancient Romans. The exact date that humans first began to mine gold is unknown, but some of the oldest known gold artifacts were found in the Varna Necropolis in Bulgaria.