Even with my favorite top-of-the-line gold detector there were several false digs. Many of the hot rocks gave a solid signal that was too much like a nugget to ignore. After trying several tests I just dug everything because it is better to be safe than leave a big, deep nugget for a more diligent gold hunter.

The type of mine dump that is best for metal detecting are the ones that consist of mixed sizes of rock and are located near some sort of excavation, commonly a shaft or adit. Sometimes the piles located along a trench dug by the miners can be productive as well.

Perhaps the most notable thing about skim placers is that they form on the top surface of gravel bars, as opposed to coarser gold placers where the weight of the gold particles allows the gold to settle down on or near bedrock.