The right speed accumulates only the heavy materials and allows all of the lighter stuff to flow through. This optimum speed is dependent on the size of the gravel you need to move through the system.

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.

The metal is expensive, not because it is rare but because of the expense to produce and work it. The minerals mined for titanium are all oxides, unlike many base metals that are mostly mined as sulfide minerals.

There are currently three controlling agencies or entities over suction dredging in California—and you can make that four if the state legislature decides to further muddy the waters with additional legislation to block suction gold dredging in the state.