If you tap a silver vein with a pickax it will turn off the ping on it.. I guess it considers it "found" at that point. Make sure you have it equipped and avoid hitting the vein until you at least mark it on your map.
Not all mountains have silver. Typically stone golems are a good sign.

Originally posted by iamteone:

I found a ship grave on a new island in my seed, equipped the wish bone, but it didn't react to any chest within the stone formation.

Depends on what was in the chest. It will only react to things you can sell / use at the trader.