Geology and mineral deposits of the Julian District, San Diego County, California
- Creators
- Donnelly, Maurice
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.
Additional Information
© 1934 California State Mining Bureau. Report submitted as part of a doctor's thesis to the Balch Graduate School of Geological Sciences, California Institute of Technology.Attached Files
Published - Donnelly_1934p331.pdf
Files
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Additional details
- Eprint ID
- 101032
- Resolver ID
- CaltechAUTHORS:20200131-111820477
- Created
-
2020-01-31Created from EPrint's datestamp field
- Updated
-
2020-01-31Created from EPrint's last_modified field
- Other Numbering System Name
- Balch Graduate School of the Geological Sciences
- Other Numbering System Identifier
- 142