Commercial quarry, Sky Blue Hill, Crestmore quarries, Crestmore, Riverside Co., California, USA

The typical pegmatite of the Commercial Quarry shows the usual variable grain size, ranging from relatively fine graphic granite up to large individual crystals of feldspar 15 or 20 cm diameter. The principal minerals, all of which are usually present, are quartz, microcline, and oligoclase or, less comkmonly, albite. At the north end, pale epidote is present, and locally also axinite, "treanorite" (allanite), prehnite, datolite, zoisite (var. thulite), colourless garnet, zircon and several zeolites. at the south end, the rather large vertical dike is characterized by 10% to 40% of andradite garnet in crystals 1 - 2 cm diameter (Am.Min.: 26: 352-381).

This quarry was cut to the 910 foot level circa 1940 to 1954.

References:
Woodford, A.O., Crippen, R.A., and Garner, K.B. (1941). Section Across Commercial Quarry, Crestmore, California. American Mineralogist 26: 352-381.

Forrester, Curt (2004). Large Clintonite Crystals from the Crestmore Quarry Riverside, California. Mineralogical Record, July/August, 2004.