Location and History
The Masonic district, in northeastern Mono County near the Nevada line, extends into Nevada. It is 12 miles northeast of Bridgeport and 16 miles northwest of Bodie. The region was prospected for some years during and after the Comstock rush of the early 1860s, but valuable ore was not discovered until 1902. The chief period of production was 1907-10, although some activity continued through the 1930s, and the Chemung mine has been intermittently worked in recent years.
Geology and Ore Deposits
The district is underlain by coarse-grained porphyritic granite and small amounts of schist. Tertiary basalt and andesite surround the area. The ore deposits are thick silicified zones or veins in the granite that strike north, northwest, or northeast. The ore consists of brecciated and recemented chert, quartz, and chalcedony that contains fine free gold. Pyrite and chalcopyrite are present in places. The ore has an open porous appearance and is often managanese-stained, and the values commonly appear in thin seams near the openings. Milling ore usually contains less than one ounce of gold per ton, but appreciable high-grade has been recovered. None of the deposits has been developed to depths of more than a few hundred feet.
Chemung $60,000, Home View, Lakeview, Maybell, Perini, Pittsburg-Liberty $700,000, Rough-and-Ready, Serita $500,000.
Boalich, E. S., 1923, Mono County, Masonic district: California Min. Bur. Rept. 18, pp. 415-416.
Eakle, A. S., and McLaughlin, R. P., 1919, Mono County, Masonic district: California Min. Bur. Rept. 15, pp. 160-165.