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Beat with a stone on copper pyrites, and it immediately begins to crumble.

This ore is often found mixed with iron or copper pyrites, and sometimes with blende.

Magnetic pyrites, copper pyrites, zinc blende and arsenical pyrites are other and less important examples, the last constituting the gold ore formerly worked in Silesia.

The substance used for the purpose was copper pyrites, which was changed to an impure sulphate of copper by the action of oil of vitriol and moist air.

Calcination is only advisable for ores which contain relatively much iron pyrites and little copper pyrites.