Two irregular, very roughly parallel, lenticular bodies of magnesium-rich limestone of Mississippian age were deposited, each approximately 400 feet thick, and whose principal portions have dips up to 45° E or ENE. The prevalent N or NNW strike conmforms to the trend of the Peninsular Range to the south, and is almost perpendicular to that of certain other metamorphic rocks near Riverside (Am. Min.: 26: 352-381).
The lower is the Chino Limestone and the upper is the Sky Blue Limestone. They are separated by gneissic hornfelses, quartz-mica schists and diorite. The beds were metamorphosed and recrystallized into marble during the early Triassic. Several later magmatic intrusions produced a complex suite of contact metamorphic minerals.
The first intrusion was of quartz diorite that penetrated the Chino Limestone. The second intrusion was of a quartz monzonite porphyry that was responsible for the classic contact metamorphism and skarn mineralogy. This latter intrusion was comprised of two pipe-like structures, ranging from 200 to 300 feet diameter. The first pipe intruded the quartz diorite and the Sky Blue Limestone. The second pipe pushed up through the metasedimentary rocks and terminated in the Sky Blue Limestone (Min. Rec. 35(4): 325-330). Numerous large and small pegmatite dikes cut the quartz monzonite porphyry and extend into the adjacent rocks, especially into the great masses of granet-rich contact rocks which have developed from the original limestone (Am. Min. 26: 351-381). The end result was a high-temperature, low-pressure contact aureole with marbles, skarn and pegmatites.
Refs.: Eakle, A.S. and Rogers, A.F. (1914) Wilkeite, a new mineral of the apatite group and okenite, its alteration product. American Journal of Science: 37: 262-267
Eakle, A.S. (1914) Some contact metamorphic minerals in crystalline limestone at Crestmore (abstract). Geological Society of America Bull.: 25: 125.
Eakle, A.S. (1916) Xanthophyllite in crystallinbe limestone. Journal of the Washington Academy of Science 6: 332-335.
Eakle, A.S. (1917) Minerals associated with crystalline limestone at Crestmore, Riverside County, California. University of California Bull. Department of Geology: 10: 327-360.
Rogers, A.F. (1918) An American occurrence of periclase and its bearing on the origin and history of calcite-brucite rocks. American Journal of Science: 46: 581-586.
Eakle, A.S. (1920) New and rare minerals formed in limestone by contact metamorphism (abstract). Geological Society of America Bull.: 31: 162-163.
Foshag, W.F. (1920) Thaumasite (and spurrite) from Crestmore, California. American Mineralogist: 5: 80-81.
Foshag, W.F. (1920) Plazolite, a new mineral from Riverside, California. American Mineralogist: 5: 183-185.
Eakle, A.S. (1921) Jurupaite, a new mineral. American Mineralogist: 6: 107-109.
Larsen, E.S. and Foshag, W.F. (1921) Merwinite, a new calcium-magnesium orthosilicate from Crestmore, California. American Mineralogist: 6: 143-148.
Foshag, W.F. (1924) Centrallasite from Crestmore, California. American Mineralogist: 9: 88-90.
Eakle, A.S. (1925) Foshagite, a new silicate from Crestmore, California. American Mineralogist: 10: 97-99.
Eakle, A.S. (1927) Famous mineral localities: Crestmore, Riversdie County, California. American Mineralogist: 12: 319-321.
Tilley, C.E. (1928) On a custerite-bearing contact rock from California Geology Magazine: 65: 371-372.
Rogers, A.F. (1929) Periclase from Crestmore near Riverside, California, with a list of minerals from this locality. American Mineralogist: 14: 462-469.
Larsen, E.S. and Dunham, K.C. (1933) Tilleyite, a new mineral from the contact zone at Crestmore, California. American Mineralogist: 18: 469-473.
Dunham, K.C. (1933) A note on the texture of the Crestmore contact rocks. American Mineralogist: 18: 474-477.
Moehlman, R.S. and Gonyer, F.A. (1934) Monticellite from Crestmore, California. American Mineralogist: 19: 474-476.
Daly, J.W. (1935) Paragenesis of the minerals a Crestmore, Riverside County, California. American Mineralogist: 20: 638-659.
Merriam, R. and Laudermilk, J.D. (1936) Two diopsides from southern California. American Mineralogist: 21: 715-718.
Kelley, V.C. (1937) Notes on mineralization at Crestmore, California. American Mineralogist: 22: 140-141.
Murdoch, J. and Webb, R.W. (1938) Notes on some minerals from southern California. American Mineralogist: 23: 349-355.
Woodford, A.O., Lauderilk, J.D. and Bailey, E.H. (1940) Treanorite, a new mineral from Crestmore, California (abstract). Bulletin of the Geological Society of America: 51: 1965.
Woodford, A.O., Crippen, R.A. and Garner, K.B. (1941) Section across Commercial Quarry, Crestmore, California, American Mineralogist: 26: 351-381.
Burnham, C.W. (1959) Contact metamorphism of magnesian limestones at Crestmore, California. Bulletin of the Geological Society of America: 70: 879-920.
Murdoch, J. (1961) Crestmore, past and present. American Mineralogist: 46: 245-257.
Jaszczak, J.A. (1991) Graphite from Crestmore, California. Mineralogical Record: 22(6): 427-432.
Veblen, D.R. and Wiechmann, M.J. (1991) Domain structure of low-symmetry vesuvianite from Crestmore, California. American Mineralogist: 76: 397-404.
Grew, E.S., Yates, M.G., Adams, P., Kirkby, R. and Wiedenbeck, M. (1999) Harkerite from the Crestmore Quarry, Riverside County, California and Cascade Slide, Adirondack Mountains, New York: A contrast in metamorphic pressure. Canadian Mineralogist: 37: 277-296.
Forrester, C. (2004) Large clintonite crystals from the Crestmore Quarry, Riverside, California. Mineralogical Record: 35(4): 325-330.
http://www.minsocam.org/msa/collectors_corner/arc/crestmoreca2.htm
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