The Whitlock district is in west-central Mariposa County five miles north of the town of Mariposa. The district is east of the Mother Lode gold belt and includes the Colorado, Sherlock Creek, and Whiskey Flat areas. The area was placer-mined soon after the beginning of the gold rush, and lode mining began shortly afterward. A number of mines were active here during the 1930s, and a few, such as the Diltz and Schroeder mines, have been intermittently prospected in recent years.
Greenstone and green schist underlie much of the district, with some slate, phyllite, and mica schist in the north portion. Granitic intrusives and serpentine are to the south. There is an appreciable number of diorite, quartz-diorite, and aplite dikes that commonly are associated with the gold-quartz veins. A northwest-trending fault extends along the west side of the district (see fig. 18).
Numerous north- and northwest-striking quartz veins contain small but rich ore shoots. The veins usually are one to five feet thick, and a number dip at low angles. The veins have a tendency to roll or bend, and it is in these bends or rolls that the high-grade pockets often occur. Much specimen ore has been produced in the district; in 1932 the Diltz mine yielded 52- and 40-pound masses of gold and quartz. The greatest depth of development is about 900 feet.
Buffalo, Champion, Colorado $50,000, Diltz $750,000 to $1 million, Geary, Golden Key $154,000+, King Solomon, Landrum, Nutmeg $180,000+, Our Chance, Permit, Schroeder $200,000 to $300,000, Spread Eagle $425,000, Whitlock $500,000.
Bowen, O. E., Jr., 1957, Mariposa County, lode mines: California Jour. Mines and Geology, vol. 53, pp. 69-187.
Costello, W.O., 1921, Colorodo district--Colorodo, Diltz, Schroeder, ond Whitlock mines; California Min. Bur. Rept. 17, pp. 93, Ill, 113, 137 ond 142.
Lowell, F. L, 1916, Moriposo County, Colorodo, Diltz, ond Whitlock mines: California Min. Bur. Rept. 14, pp. 579, 581, ond 599-600.
Ransome, G. L, 1900, Mother lode district folio: U.S. Geol. Survey Geol. Atlas of the U.S., folio 63, 11 pp.