![]() ![]() So where a river cuts through gold bearing rock, and then slows down as it hits a flatter/wider river bed, gold will concentrate in a 'placer' deposit, allowing extraction of gold particles by panning and the modern day industrial equivalents. Because of its extreme density gold will readily fall out of suspension as water slows down. On or near the surface there is alluvial gold which has been concentrated by the effects of running water, for example in rivers. ![]() The process of gold concentration happens both above and below the surface of the Earth. So gold ore needs to be concentrated by about 1,000 times above the average to become viable. A lower grade gold ore would contain something like 5 grams per tonne (5 parts per million). It needs to be concentrated by natural variations to about 30% to be considered an ore, indicating a required geological concentration of about 5 times. Iron, for example, accounts for an average 5.8% of the content of the Earth's crust. Rising energy costs always impact mining viability.Īt different points concentration of minerals within the earth's crust varies from their average, and it is those variations which produce workable ores. The energy required to heave, grind and process ore is itself valuable and places a lower limit on the quality of ore which can be profitably worked. The technology of extraction is expensive primarily because the process always requires the manipulation of large physical quantities of ore for small results. Gold's average concentration in the Earth's crust is 0.005 parts per million. The cost of pumping 1,000 tonnes of seawater for processing would considerably exceed the tiny amount of gold it would yield. Interestingly there is also gold in solution in seawater, however although the aggregate quantity is large (because the oceans are huge), the concentration is low and renders extraction beyond any reasonable technology. Nuggets are an exception, but account for the tiniest portion of discovered gold. According to all geological experience it is found almost entirely in low concentrations in rocks. As a private store of wealth (~15% of the global supply).As a public store of wealth - backing monetary systems (~20% of the global supply).As a personal adornment, where its colour and its relationship to wealth contribute to its use in jewelry manufacture (~60% of the global supply).Of all the gold dug from the Earth the bulk of it us used in these three ways:. However its genuinely practical uses are numerically insignificant. It is used in dentistry and in the manufacture of some electronics which require high quality non-corrosive contacts. ![]() Gold finds a small number of industrial uses arising from its physical qualities. It is remarkable for its rarity, density, softness, and its very good electrical conductivity. It is largely inert, which means:- (i) It is almost totally immune to decay, (ii) it is not very useful in any industrial/chemical processes which use it up and (iii) it is easy to store cheaply for long periods. Gold is a chemical element so it can only be found, not manufactured.
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