ocr: Some of the metals in the Earth's crust are more: abundant than others. Iron, for example, is much more abundant than gold. The amount of a metal in the Earth's crust: is called its crustal abundance. In most places, metals are only present in tiny amounts: their crustal abundance is low. Since such: small quantities of a metal are not profitable to mine, metals are only extracted from placesi in the crust where geologic processes have concentrated them in one place. Any rock that contains high concentrations of a metal, and which can be easily and profitably extracted, is known asa metallic o ...
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