The process is rarely applied to ores direct; free-milling ores are generally amalgamated, and the tailings and slimes, after concentration, operated upon.
It is best adapted for free-milling ores, especially after the bulk of the gold has been removed by amalgamation.
A silver ore is either free-milling or refractory, that is, the silver mineral is readily amalgamated or it is not.
In free-milling ore the silver is present either in the native state, or as chloride or as simple sulphide.
The yield in silver is low unless the ores are exceptionally free-milling; the bullion produced is high-grade, as refractory silver minerals are hardly attacked.