Many areas of Peridot Mesa have been mined for gem material. The gem-bearing layer of the basalt varies from 3 to 35 meters in thickness and consists of shattered masses of olivine encased in a vesicular basalt. The canyon at the northern end of the mesa has provided relatively easy access to the gem zone and has been heavily worked. Some heavy equipment, drilling, and blasting are being used to get to this zone, but most of the mining is still done by hand.