California State Gem Mine (Dallas Gem Mine; Benitoite Mine; Benitoite Gem Mine; Gem Mine), Dallas Gem Mine area, San Benito River headwaters area, New Idria District, Diablo Range, San Benito Co., California, USA
|Latitude & Longitude (WGS84):||36° 20' 9'' North , 120° 36' 19'' West|
|Latitude & Longitude (decimal):||36.33611,-120.60528|
|Köppen climate type:||Csb : Warm-summer Mediterranean climate|
A former gemstone and specimen mine located in the NE¼ sec. 25, T18S, R12E, MDM, 1.2 km (4,000 feet) SSW of Santa Rita Peak at the headwaters of the San Benito River and New Idria, W side of the Diablo Range, about 25 miles N of Coalinga.
Mineralization is natrolite veins cutting a glaucophane schist inclusion in a serpentinite body.
Note: The majority of specimens from this locality have been prepared by dissolving away the enclosing natrolite with hydrochloric acid.
31 valid minerals. 6 (TL) - type locality of valid minerals.
Rock Types Recorded
Select Rock List TypeAlphabetical List Tree Diagram
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
|Late Jurassic - Middle Jurassic|
145 - 174.1 Ma
|Ultramafic rocks, chiefly Mesozoic, unit 3 (Coast Ranges and Western Klamath Mountains)|
Age: Jurassic (145 - 174.1 Ma)
Stratigraphic Name: Josephine Peridotite
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.