The rarity of silver is expressed by its occurrence in igneous rock of just 0.07 parts per million. The potential of a silver deposit is evaluated by determining the amount of metal it contains. Silver is rarely found alone in mineral ores. Copper, manganese, iron, lead and zinc are metals commonly found in silver-containing ore. This complicates silver mining economics, because the presence of other metals will also affect the value of the deposit.
Methods employed to mine silver include both underground and open-pit procedures. Determination of the method to be used is based upon whether it is most likely to glean the largest amount ore from the deposit. Sometimes both methods are used in the same area.
Silver-containing ores are first mined, and then processed by crushing and grinding. The resulting composite can be separated by mechanical or chemical means. Most silver ores are classified as sulfides, which may be easily separated by flotation.
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