Eventually, the big corporations took over, made it into an industry and started controlling the supply AND price of it.

http://motherboard-assets.s3.amazonaws.com/content-images/article/modern-day-prospectors-will-haul-12000-gallons-of-cyanide-from-nevada-to-mine-for-gold-in-utah/3833fb6b626bc628459fb27f499e0255_vice_630x420.jpg