An old neighbor for years and a friend, used to hunt gravel bars in the creeks and rivers around here. He had a masive collection of perfect stuff, and buckets full of broken stuff. I went with him a few times, and he would walk a grid over every gravel bar he came to, with a stick, and flip out everything that looked suspect. I would do like him, and couldn't find a thing! He always came away from a gravel bar with some stuff, sometimes nice and sometimes broken!