[quote treasurefiend]What is the zinc mark on the Ace 250??? I just see penny...[/quote]it is there, look under the penny mark, the zinc pennies on mine fall just left under it, and the coppers are on the right side under it. Air test it with one of each and you should see the difference. I dig every zinc signal because you NEVER know what is in the ground. The gold ring I found bounced from zinc penny to pull tab