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Jensen Quarry (Oak Quarry), Jurupa, Jurupa Mts, Riverside Co., California, USA

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Latitude & Longitude (WGS84): 34° 1' 32'' North , 117° 25' 54'' West
Latitude & Longitude (decimal): 34.0255555556, -117.431666667

A former limestone/marble quarry located in sec. 5, T2S, R5W, SBM, 4.7 km (2.9 miles) NW of Jurupa and 4 miles W of Riverside.

First worked during World War I for marble for cement manufacture by Riverside Cement Company (the same company that owned the more famous nearby Crestmore deposit). Closed in 1927; reopened by Riverside Cement Company in 1948; closed again in 1955. Snow Rock Corporation leased the northeastern section of the quarry from the early 1960s until 1971 to mine dolomitic marble (too high in Mg for cement) for granulated roofing material. The last period of commercial activity was 1974-1979, when Riverside Cement Company removed the last of the cement-grade marble. Since 1979, the remaining pegmatites, impure marbles and other contact metamorphic rocks have been of interest only to field collectors.

In the late 1990s, the abandoned quarry was purchased by a golf club and remodelled into a spectacular course, with white marble and pegmatite cliffs as backdrop, now the "Landmark Golf Club at Oak Quarry" (renamed Oak Quarry by the golf club; not known as Oak Quarry during its active extractive years), so field collecting is no longer allowed. But the management are proud of the mineralogical heritage of their site, and the course holes bear fanciful mineral names: Biotite Bluff, Calcite Canyon, Garnet Meadow, Graphite Tower, Gypsum Gully, Limestone Dome, Magnesite Terrace, Marble Ridge, Microlite Ledge, Muscovite Marsh, Opal Outcrop, Pyrite Perch, Quartz Corner, Spinel Slide, Tourmaline Tower, Tremolite Pass, Zircon Tumble. The club house has a glass case displaying Jensen Quarry specimens, donated mainly by local collectors Anne Seminaris Davila and Nick Rose.

Mineral List

81 valid minerals.

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.


Rocks & Minerals (1932): 7: 98.

Rocks & Minerals (1933): 8: 80.

Pabst, Adolf (1938), Minerals of California: California Division Mines Bulletin 113.

Murdoch, Joseph & Joseph J. Fahey (1948), Geikielite, a new find from California (abstract): Geological Society of America Bulletin: 59: 1341-1342.

Murdoch, Joseph & Joseph J. Fahey (1949), Geikielite, a new find from California: American Mineralogist: 34: 835-838.

MacKevett, Edward Malcolm, Jr. (1951), Geology of Jurupa Mountains, San Bernardino and Riverside Counties, California: California Division Mines, Special Report 5, 14 pp.

Anonymous (1955), World news on mineral occurrences: Rocks & Minerals: 30: 141-142.

Cooney, R.L. (1956), The mineralogy of the Jensen and Henshaw quarries near Riverside, California: Unpublished Master’s thesis, University of California at Los Angeles.

Mineralogical Magazine (1964): 118.

Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 68, 115, 137-138, 198, 207, 222, 285, 288, 295, 371.

Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 55, 70, 72, 76, 85, 90, 94, 97-98, 103, 130, 143, 145, 146, 150-151, 170, 173, 200, 211, 221, 226, 236, 287, 316, 319, 336, 348, 362, 367, 368, 380, 387, 392, 398, 406, 420, 428, 431, 434, 444, 458, 461, 475, 479, 483, 486, 490, 498, 502, 507.

Devito, F. and Ordway, A. (1984). The Jensen Quarry, Riverside County, California. Mineralogical Record: 15(5): 273-290.

Lapis (2003): 28(12): 9.

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