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Material World

Ore

An ore is a mineral or rock from which a metal can be extracted at a profit, and every word of that is doing work. It is not a statement about composition: plenty of minerals contain copper and only a few are copper ores. Grade, depth, the price of the metal and the process available all enter into it.

Which means the same rock can stop being an ore and start again. Copper ore grades have fallen for a century as flotation and larger equipment made poorer rock economic, and deposits abandoned as worthless have been reopened on the same material at a higher price.

Each of these uses is established and cited on its own. Whether something counts as an ore, for instance, depends on grade, price and era — and those qualifications are shown alongside it.