Geology and mineral deposits of the Julian District, San Diego County, California

Abstract

The Julian region, in the central part of San Diego County, California, includes the Julian, Banner, several other less important mining districts, and the Stonewall Mine on the Cuyamaca land grant. In addition to being one of the few areas in the Peninsular Range of southern and Baja California that have yielded notable amounts of gold, it constitutes geologically a diagnostic part of the range because of the land forms, structures, and rock formations exposed. Discovered in 1870, the Julian and Banner districts produced in the next several years $2,500,000 in gold from oxidized ore, having an average tenor of $50 a ton. This came from narrow veins which were only in a few instances mined below the water-table. The Stonewall Mine, worked continually from 1870 until shut down in 1893, produced $2,000,000 from a large ore body extracted to a depth of 600 feet. The Julian and Banner districts had a brief mining revival during the '90s.