Geology, Palaeontology & Archaeology / Re: Which rocks contain metallic flakes resembling silver and gold?« on: 26/08/2017 09:19:12 »
Lot of granites do have quite high gold concentrations inside, but are not at all economical to mine because they are so hard, and the energy required to grind them to powder to enable the gold to be extracted is more than the value of the gold. Thus most gold comes from softer dolerites where it is easier to crush them, and we do not really mine seawater even though it has a similar gold content, as concentrating the gold is hard in that case. However a lot of the flakes in rocks are also various forms of mica, which can look like gold and silver flakes.
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