I've been observing several prospecting video's and the common theme seems to be high resolution coil (e.g. small), or elliptical and the higher frequencies. I would also guess that wheat kernel sized nuggets would be the most challenging and probably more common than larger sized stuff (so small gold particles would require a higher resolution coil, to improve detectability). I used to do a lot of prospecting in Idaho, and Alaska w/out a metal detector, and along with the technology there are some good common sense principles to use when searching for gold. Especially in water drainage basins, or arroyo's (dry washes). Principally that gold has a high weight relative to the rest of the minerals and will tend to seek it's way to bedrock, or behind/under boulders. In water this is due to how quickly gold flocculates (e.g. sinks) in a solution. It's also helpful to understand that a streambed, dry wash only "throws" gold at certain times in it's history so don't be limited to the bottom deposits (richer ones) sometimes are much higher in the canyon and what you are seeing is a sample of what's there. Look for rounded rocks (water worn) at higher elevations above the current waterway or arroyo, also look for bedrock outcroppings that would have acted as an eddy maker
during waterflow, as this tends to concentrate the gold as well. (these little hints always seemed to improve my finds)
It's a lot of fun looking and finding I hope you have many success's as you get out and bang the bottoms.
