I have gone garnet prospecting at the official state-sanctioned Emerald Creek Garnet Area in the Idaho panhandle. They ship in tailings from the mines for people to process by hand, first by sifting out the sand from the gravel, and then by washing the gravel in sluice boxes to find the gemstones. There are also places to go rockhounding in the wild, but this was a fun way to get garnet fever without getting lost in the wilderness.