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High-grade gold ore from the Harvard Mine, Jamestown, California, a wide quartz-gold vein in California's Mother Lode. Specimen is 3.2 cm (1.3 in) wide. Specimen is 3.2 cm (1.3 in) wide. Various theories of ore genesis explain how the various types of mineral deposits form within Earth's crust .
The lithosphere is the dominant reservoir of gold, containing an estimated 2.6x10 13 Mg. [1] Today, gold exists primarily as electrum, in hard rock deposits like tellurides, and as particles in placers in Earth's crust. Gold cycling starts with the microbial weathering of gold-bearing rocks and minerals which mobilizes gold in the environment ...
The content of gold within these deposits is largely variable, and can be a factor in the economic value of the deposit. The gold contents of all deposits averages 0.41 g/t Au, with the majority of worldwide deposits averaging less than 1 g/t Au. [2] The occurrence of native gold mineralization. Example from Kalgoorlie Australia.
In their chronology for Earth, Hazen et al. (2008) separated the changes in mineral abundance into three broad intervals: planetary accretion up to 4.55 Ga (billion years ago); reworking of Earth's crust and mantle between 4.55 Ga and 2.5 Ga; and biological influences after 2.5 Ga. [1] [12] They further divided the ages into 10 intervals, some ...
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
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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.