Peridot Mesa

The olivine here is remarkably free from alteration, which is US Geological Survey language for crystals that came out clean.

Peridot Mesa is a producer of olivine and gemstone in Gila County, Arizona, and the survey notes the olivine occurs both as euhedral crystals and as rounded grains, with apatite and magnetite as gangue. The only alteration it records is an occasional slight yellow stain from iron oxide. The host is mafic volcanic rock, and the survey maps both the olivine-bearing flow and, separately, an olivine-rich zone running above 30 per cent olivine.

Before you go, understand whose ground this is. The mesa lies within the San Carlos Apache Indian Reservation, so the tribe decides who collects here and on what terms, not the state and not the federal government. Treat that as the first question to settle, not the last.

The community below takes its name from the stone. Peridot, in Western Apache Tséé Dotłʼizh, meaning blue rock, is an unincorporated community and census-designated place spanning Gila and Graham counties, with a population of 1,350 at the 2010 census. It is named for the mineral, which is found in the basalt flows nearby.

The geography is easy to picture. US Route 70 runs through the community, 20 miles west to Globe, the Gila county seat, and 57 miles southeast to Safford, the seat of Graham County. The San Carlos River flows south through the place and forms the boundary between the two counties. Coolidge Dam, which impounds San Carlos Lake on the Gila and San Carlos rivers, is 11 miles to the south.

The survey even records how the mesa is reached: from San Carlos by the powerline road, which ascends and crosses Peridot Mesa. That is a useful sentence, but it describes a route, not a permission.

Be very clear: this is SOVEREIGN TRIBAL LAND and collecting is controlled entirely by the San Carlos Apache, mined by tribal members; outsiders do not dig here.