They call it the Grand Canyon of the Mojave, which is overselling the scale and underselling the oddity. The Mojave River runs mostly underground across the desert, and at Afton the bedrock forces it to the surface, so you get a genuine flowing river with riparian trees in the middle of some of the driest country in North America. The canyon walls it cut are banded and eroded into badland shapes, and a working railroad runs the length of it.
For a rockhound the draw is silica. The canyon and its side washes have been collected for generations for agate, including plume agate and sagenite, jasper and agate-jasper, chalcedony, opalite and petrified wood, all weathered out of volcanic country and concentrated in the gravels. The washes do the sorting for you, which is why this is a walk-and-look locality rather than a dig-a-hole one.
The land status is the thing to get right. Afton Canyon is a BLM Area of Critical Environmental Concern inside the Mojave Trails National Monument, administered by the Barstow Field Office. Rockhounding for personal use is allowed on BLM ground outside designated wilderness, in reasonable quantities. The Barstow office's own working definition of reasonable for decorative stone is memorable: no more than you can carry in the boot of a car. Motorised travel is restricted to designated routes, and the wilderness and ACEC boundaries are real lines that matter.
Go between October and April. From May to September this is regularly over a hundred degrees and the combination of heat, deep sand and no phone signal has hurt people who thought it was a day trip. It is off Interstate 15 at the Afton turnoff, about thirty two miles east of Barstow, and the approach road is sand. Carry water for twice as long as you plan to stay.
Agate, jasper
Other places on the map within a couple of hours.
