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A variety of gold deposits are formed in accretionary orogens, including orogenic gold deposits. [38] Orogenic gold deposits are typically located in metamorphosed fore-arc and back-arc regions, as well as in the arc [3] and show a close spatial relationship to lamprophyres and associated felsic porphyry dikes and sills. [39]
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. Various theories of ore genesis explain how the various types of mineral deposits form within Earth's crust.
All of the deposits shown that are north and east of the Battle Mountain-Eureka trend (and many of the others) are Carlin-type gold deposits. Source: USGS Goldstrike (Post–Betze) Mine , Carlin Trend , Nevada, the largest Carlin-type deposit in the world, containing more than 35,000,000 ounces of gold. [ 1 ]
The Zangezur copper-molybdenum complex possesses large molybdenum reserves that are concentrated in the Kajaran deposit. Besides molybdenum, Armenia has significant deposits of copper and gold; smaller deposits of lead, silver, and zinc; and deposits of industrial minerals, including basalt, diatomite, granite, gypsum, limestone, and perlite. [2]
An ore shoot is a hypogenic mass that is deposited in veins within a planar channel or lode, found in a shear or fault zone, fissure or lithologic boundary. [1] The ore shoot is the area of concentration which contains a primary ore along the veins present in the rock, and consists of the most valuable part of the deposit.
After the majority of the gold input was finished, many large scale tectonic and geological events have occurred. Such event ages obtained by the monazite, Rb–Sr, and paleomagnetic studies. During these events the gold was likely remobilized and other ore minerals (e.g. pyrite) formed to create the present day state of Sukhoi Log.
An overview of one of the regolith-hosted rare earth element deposits (a type of Rare Earth Element mine) in South China [1]. Regolith-hosted rare earth element deposits (also known as ion-adsorption deposits) are rare-earth element (REE) ores in decomposed rocks that are formed by intense weathering of REE-rich parental rocks (e.g. granite, tuff etc.) in subtropical areas. [2]
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.