Surprise Mine, Ramona, Ramona District, San Diego Co., California, USA
|Latitude & Longitude (WGS84):||33° 3' 10'' North , 116° 47' 20'' West|
|Latitude & Longitude (decimal):||33.0527777778, -116.788888889|
A gem-bearing granite pegmatite deposit located 7.4 km (4.6 miles) east of Ramona. Elevation approx. 1997' AMSL.
12 valid minerals. 1 erroneous literature entry.
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 Cretaceous - Middle Jurassic|
66 - 174.1 Ma
|Mesozoic granitic rocks, unit 2 (Peninsular Ranges)|
Age: Mesozoic (66 - 174.1 Ma)
Stratigraphic Name: Bonsall Tonalite; Bradley Granodiorite; Cactus Quartz Monzonite; Cajalco Quartz Monzonite; Corona Hornblende Granodiorite Porphyry; Domenigoni Valley Granodiorite; Escondido Creek Leucogranodiorite; Estelle Tonalite; Fargo Canyon Diorite; Green Valley Tonalite; Home Gardens Quartz Monzonite Porphyry; Indian Mountain Leucogranodiorite; Lakeview Mountain Tonalite; Lake Wolford Leucogranodiorite; La Sierra Tonalite; Mount Hole Granodiorite; Rattlesnake Granite; Roblar Leucogranite; San Jacinto Granodiorite; Stonewall Quartz Diorite; Woodson Mountain Granodiorite
Comments: Peninsular Ranges. Primarily tonalite, granodiorite, and minor quartz monzonite and granite. Emplacement ages mostly 80 to 105 Ma in eastern part of area and 105 to 140 Ma in western part; minor Jurassic rocks in central part
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. 
Ford, William Ebenezer (1906), Some interesting beryl crystals and their association: American Journal of Science, 4th. Series: 22: 217-223.
Merrill, F. J. H. (1914), Geology and Mineral Resources of San Diego and Imperial Counties: Gems, Lithia Minerals. California State Mining Bureau, San Francisco, Cal. California State Printing Office, December. Chapter 1: 72.
Rocks & Minerals (1943): 18: 207.
Sinkankas, J. (1957a) Recent gem mining at Ramona, San Diego County, California. Gems and Gemology: 8: 367-373.
Sinkankas, J. (1959) Gemstones of North America. D. Van Nostrand Co., New York, 675 pp.: 103.
Snyder, Doris (1962), Wonderful world of pegmatite minerals: Part I: Gems & Minerals, No. 293: 24-26, Feb, 1962.
Weber, F. H. (1963a), Geology and mineral resources of San Diego County, California. California Division of Mines and Geology, County Report 3: 87, 112, Pl. 5.
Simpson, Dale R. (1965) Geology of the central part of the Ramona pegmatite district, San Diego County, California. Clifornia Division of Mines and Geology Special Report 86: 22.
Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 103, 195, 368.
Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 454, 499.