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Ortega Mine (Old Dominion Mine), Rancho Santa Margarita, Santa Ana Mts, Orange Co., California, USA

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A former Ag-Pb-Zn-Au-Cu mine located about 8½ miles E of Rancho Santa Margarita and about 6 miles W of Lake Elsinore (Riverside County).

Mineralization is hosted in metamorphic rock and granite.

Local structures include a fault which displaced the vein at its northern end. The strike of the fault is N, with a 35W dip.

Production includes 100 tons of ore shipped to Midvale, Utah in 1942 that assayed 0.02 ounces per ton gold, 25.8 ounces per ton silver, 0.3 percent copper, 3.5 percent lead, and 3.1 percent zinc (Tucker and Sampson 1943c).

Mineral List

7 entries listed. 6 valid minerals. 1 erroneous literature entry.

The above list contains all mineral locality references listed on This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


Tucker, W. Burling & Reid J. Sampson (1943c), Current mining activity in southern California: California Division Mines Report 39(2) 123-124.

Goodwin, Joseph Grant (1957) Lead and zinc in California. California Journal of Mines and Geology, Division of Mines (Report 53): 53(3&4): 586.

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