Big Horn Mine

Los Angeles County, California, United States

GoldSilverCopperLeadZincArsenic

⌖ Show on map USGS source ↗

Commodities

PrimaryGold

SecondarySilver

TertiaryCopper, Lead, Zinc, Arsenic

Commodity typeM

Deposit

Deposit typeHydrothermal vein and replacement

Model273: Low-sulfide Au-quartz vein

Deposit sizeM

Orebody formTabular; gold mineralization occurs within a zone of brecciation and cataclasite formation along the gently northwest-dipping Vincent Thrust fault zone. Disseminated gold occurs in the Pelona Schist near the Vincent Thrust.

Ore controlPermeable, crushed rock between the upper and lower strands of the Vincent Thrust Fault.

Materials

Ore mineralsGold, Pyrite, Chalcopyrite, Galena, Arsenopyrite

GangueSchist, Gneiss, Andesite

Geology

Host rockAmphibolite,Cataclasite,Schist,Gneiss · "San Gabriel Gneiss", "Pelona Schist"

Associated rockGneiss,Schist,Quartz Monzonite,Volcanic Rock (Aphanitic)

StructureVincent Thrust fault; San Andreas Fault; Punchbowl Fault, San Gabriel Fault; northwest striking normal faults in Big Horn Mine area; regional arching of the San Gabriel Mountains basement complex and Vincent Thrust along a northwest-trending axis in the region around the Big Horn Mine.

Tectonic settingBack-arc thrust belt\n\nThe Big Horn Mine is located near the crest of the San Gabriel Mountains, an east-west trending range along the southwest side of the San Andreas Fault in the central part of the Transverse Range Province of southern California. Uplift of the range began a few million years ago and is still going on as a product of convergence between the North American and Pacific Plates along the bend in the San Andreas Fault. It was accomplished by reverse faulting along the southern range margin and broad arching across the interior and northern margin, with uplift extending northeastward across the San Andreas Fault. The relatively simple pattern and style of uplift are superimposed upon the complex structure of rocks exposed within the range (Ehlig, 1981, pg.254)

AlterationSilicification\nPyritization\nCarbonatization

Economic & production

Development statusPast Producer

Discovery year1891

Identification

Deposit ID10310697

RegionNA

Data scoreA

Coordinates34.35639, -117.74361

References

Portions of various unpublished reports and reports from various Internet websites, contained in CGS Minefile Folder No. 330-3745.Clark, W. B., 1988, Mount Baldy District in Gold Districts of California, Sesquicentennial Edition, California Gold Discovery to Statehood: CGS (formerly CDMG) Bulletin 193, Page 174.Conrad, R. L., and Davis, T. E., 1977, Rb/Sr Geochronology of cataclastic rocks of the Vincent thrust, San Gabriel Mountains, southern California [abstract]: Geol. Soc. America Abstracts with Programs, v. 9, no. 4, p. 403-404.Ehlers, E. G. and Blatt H., 1980, Petrology: Igneous, Sedimentary, and Metamorphic: W. H. Freeman and Co., San Francisco, 732 p.Ehlig, P. L., 1981, Origin and tectonic history of the basement terrane of the San Gabriel Mountains, central Transverse Ranges; in Ernst, W. G., Editor, 1981, The tectonic development of California, Rubey Volume I: Prentice-Hall, Inc., Englewood Cliffs, New Jersey 07632, Pages 253-283.Hamann, W. E., 1985, Geology and geochemistry of the Big Horn gold mine, San Gabriel Mountains, southern California: M.S. Thesis, University of California Los Angeles (UCLA).Inspiration Mines, Inc., 1985, Big Horn Mine Feasibility Report.Jones, A. G., 1983a, Report on the Gig Horn Mine for Harbour Management Ltd.Miller, C. C., Jr., 1938, Report on Big Horn Mine, Los Angeles County, California, owned by Fenner Mines, Inc., 15 pages (The date of the report is written in pencil on the front of the report; the report is contained in CGS Minefile Folder No. 330-3745.)Miller, F. K., and Morton, D. M., 1977, Comparison of granitic intrusions in the Pelona and Orocopia schists, southern California: U.S. Geol. Survey Jour. Res., v. 5, p. 643-649.Ristorcelli, Steve, January 15, 1988, Summary report and recommendations on the big Horn property, Los Angeles County, California: report prepared for Centurion Minerals, Ltd. And contained in the CGS (formerly CDMG) Minefile archives.Shelton, J. S., 1955, Glendora volcanic rocks, Los Angeles basin, California: Geol. Soc. America Bull., v. 66, p. 45-90.Van Nort, S. D., 1986, Report on the big Horn Mine - An Evaluation of Recent Exploration - for Great Pacific Resources.