Problem with silver ingots

Recently all my ingots have this coloring to them, is it gold/copper or ?.. I work in a shared studio and think maybe someone was contaminating the crucible with different metals…Is there anyway to salvage the silver?

thanks.

Most likely surface oxide. How do they roll or forge?

Please excuse any typos-- curse my clumsy digits…

I think you’re right, I cleaned them up and they seem fine. Guess I panicked because it just started happening all of a sudden, and usually they don’t look anything like that at all.