Peridot Mesa (Peridot occurrence 38), San Carlos, San Carlos Indian Reservation, Gila Co., Arizona, USA
|Latitude & Longitude (WGS84):||33° 19' 49'' North , 110° 29' 35'' West|
|Latitude & Longitude (decimal):||33.33028,-110.49306|
|Other regions containing this locality:||Sonoran Desert, North America|
|Köppen climate type:||BSk : Cold semi-arid (steppe) climate|
A peridot/olivine mine located in secs. 18, 19 & 30, T1S, R19E; and in secs. 22-27, T1S, R18E, immediately SW of San Carlos. This site has been described as the most productive peridot locality in North America.
Mineralization is a mesa capped by a basalt flow from 10 to more than 100 feet thick, underlain by flat-lying tuffs, siltstones & gravels. These sedimentary rocks are regarded as the equivalent of the Gila Conglomerate and therefore of Pliocene or Pleistocene age. The peridot occurs in roughly ellipsoidal bombs, or segregations, in basalt & cinders erupted from a volcanic cone that occupies the SW corner of the mesa. It is present as euhedral crystals and as rounded grains. The ellipsoidal segregations containing the peridot make up 25 to 40% of the rock volume and average 3 to 8 inches in maximum diameter.
Workings: Mined intermittently by individuals (up to 50), who worked scattered portions of the deposit using hand methods. Also was mined by 5-10 person operations that are more mechanized. Most stones are gathered from debris resulting from the erosion of basalt. Prime locations are around the rim of the volcanic cone, in washes adjacent to the cone, and in small canyons that breach the north rim of the mesa.
Assay data: The olivine zone should maintain a minimum olivine content of 30% to be economical. The portions of the deposit olivine-rich zone with greater than 30% olivine are: SE¼ sec. 15, S½ sec. 14, sec. 22, N½ and SW¼ sec. 23, NW¼ sec. 26, and the NE¼ sec. 27, T1S, R18E.
6 valid minerals.
Rock Types Recorded
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Entries shown in red are rocks recorded for this region.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
|Holocene - Zanclean|
0 - 5.333 Ma
|Holocene to middle Pliocene basaltic rocks|
Age: Cenozoic (0 - 5.333 Ma)
Description: Mostly dark-colored basaltic lava and cinders young enough that some original volcanic landforms are still apparent. Includes a small amount of andesite, dacite, and rhyolite. Rocks of this map unit are largely restricted to six areas widely distributed in Arizona: San Francisco and Uinkaret volcanic fields in northern Arizona (0-4 Ma); Springerville (0-4 Ma) and San Carlos (0-2 Ma) volcanic fields in east-central Arizona; and San Bernardino (0-1 Ma) and Sentinel (1-4 Ma) volcanic fields in southern Arizona. Rocks of this unit are also present in the extreme southwestern part of Arizona where they were erupted at the edge of the Pinacate volcanic field (0-2 Ma) in northwestern Sonora. (0-4 Ma)
Comments: Largely in six volcanic fields: San Francisco, Unikaret, Springerville, San Carlos, San Bernardino, and Sentinal.
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052.