Wyrmsun's next patch will feature the addition of silver and copper gathering. These metals are gathered much in the same way as gold, being available both through metal rocks and by building a mine on top of a deposit. Once delivered, silver and copper are converted to gold - at a 50% rate for silver and a 25% rate for copper.
The inclusion of these two new less valuable metals creates new strategic decision-making possibilities for players. A silver site might be safer than a more distant gold site - should the player then risk securing the far away gold, or settle for the nearer silver? If no gold is available, should workers be diverted from other functions to copper and silver gathering to make up for the smaller income?
I leave you with a preview of a copper deposit: