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.

Silver recovery from low-level solutions is frequently done in a cell that has a cathode with 2 to 5 or more times the surface area as the anode.

There were nice sections of vein material at the end of several drifts, like they just stopped work one day and walked away.

…there is an easy way to create a reasonably accurate map without any fancy instruments.