In several mines all over the world, Ag is very economic when it is a by-product. Major examples are:
1) In galena-dominated VMS (igneous).
2) In carbonate-hosted galena ores, Mississippi Valley-Type Sulphides (MVTS).
3) In association with epithermal gold veins and lodes with high content of Ag as a metal and electrum alloy.
4) In more rare cases, in silver quartz veins like in Germany and in this case sulphide minerals of Ag are essential, e.g. argentite and wire-like native silver as well.