Move around a bit and keep digging you'll either find the edge of the silver node or you'll find a skeleton and a silver necklace (used to make the treasure chest decoration) or very rarely a wooden chest that will contain gems and at least one silver necklace. When you take the silver necklace the wishbone goes silent just like when you mine out all the silver in the silver node. Sometimes you'll find even a 2nd or 3rd silver node.
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