I like metalurgy in VS. Seing the devs are going for realism i think it would be great if cupelation mechanic was added to separate the small amounts of silver and other precious metals potentialy present in the galena.
Cupellation is a historic way of separating precious metals from lead by selectively oxidising and absorbing non noble metals in a cupel. A dish or bead from bone ash.
This is how i propose it would function in game.
First you mine and smelt galena into lead ingots like we do allready. Once ingots cool down howering with your mouse above them will show you how many % of silver and or gold does it contain. Ingots can still be used as they are now but should you wish to extract precious metals you would then mix ground bones and clay and clayform them into a cupel and fire it like any other clay item.
Then you would place the cupel into a pit kiln or fireplace, heat it up, and place at least 5 lead ingots into it ( that way you would get 1 silver nugget if the ingots contain 1% silver). When cupelation is complete and the cupel cools down you would take out your silver, gold or electrum (if both silver and gold are in the ore) nuggets. The used up cupel can then be shattered with a hammer and smelted to recover pure lead.
Edit: This mechanic could also be aplied to bismuth ore because bismuth minerals IRL can also contain silver.
Check this if you want to learn more: