Oroville District

Site Name

Primary: Oroville District

---

Commodity

Primary: Gold
Secondary: Platinum

---

Location

State: California
County: Butte
District: Oroville District

---

Land Status

Not available

---

Holdings

Not available

---

Workings

Not available

---

Ownership

Not available

---

Production

Not available

---

Deposit

Record Type: District
Operation Category: Past Producer
Deposit Type: Stream placer
Operation Type: Surface-Underground
Discovery Year: 1849
Years of Production:
Organization:
Significant: Y
Deposit Size: M

---

Physiography

Not available

---

Mineral Deposit Model

Model Name: Placer Au-PGE

---

Orebody

Form: Irregular

---

Structure

Not available

---

Alterations

Not available

---

Rocks

Name: Sand and Gravel
Role: Host
Age Type: Host Rock
Age Young: Quaternary

---

Analytical Data

Not available

---

Materials

Ore: Gold
Ore: Platinum
Gangue: Quartz

---

Comments

Comment (Commodity): Gangue Materials: Metamorphic rock, igneous rock, quartz (as clasts)

Comment (Deposit): One of the most productive placer districts in California, production of gold was estimated by Clark (1970) at $55 million. The gold is present in river gravels and adjacent terrace gravels on the flood plain of the Feather River. The gravels rest on a bedrock of soft but compact andesite and rhyolite tuff. Coarse boulders, which become finer downstream, alternate with sand layers.

Comment (Geology): REGIONAL GEOLOGY The Oroville District is situated at the westernmost edge of the Sierra Nevada geologic province where it adjoins the Sacramento Valley This province is characterized by extremely complex lithologies and structures that were assembled through various plate-tectonic processes. Paleozoic-Mesozoic metamorphic complexes intruded by various Mesozoic plutons compose the basement of the province. This basement is overlain in places by erosional remnants of Cenozoic volcanic and sedimentary rocks, including gravels. Most of these various lithologies contain gold in places. Structurally, the metamorphic rocks and some of the plutonic rocks of the basement have been deformed by folding and faulting. The major fault zones typically trend northerly or northwesterly, although in places intrusion of the younger plutons has deformed some of the zones so as to assume other trends as well. In contrast, the overlying Cenozoic rocks are relatively undeformed. LOCAL GEOLOGY The Oroville District is mainly associated with modern alluvial deposits of the main drainage of the Feather River where it discharges into the Sacramento Valley after passing through the Sierra Nevada basement terranes. The materials in these deposits have been derived by erosion of the various basement and older Cenozoic rocks at higher elevations. In places, the basement rocks contain gold within quartz veins and altered rock, while the Cenozoic deposits contain placer gold derived by erosion of these older basement rocks. Erosion of both the gold-bearing basement rocks and the older Cenozoic rocks provided the gold that was eventually deposited in the modern placer deposits along the main Feather River. Platinum was probably derived from erosion of ultramafic rocks and serpentinite in the Sierra Nevada basement.

Comment (Identification): This district is mainly a dredging field that extends from just west of the city of Oroville southwest along the Feather River to a point about five miles due east of the town of Biggs. The field is one to two miles wide and nine miles long. The extent of the district, as defined by distribution of tailings, is more clearly displayed on the Gridley 15-minute quadrangle than on the corresponding 7.5-minute quadrangles.

Comment (Location): Location selected for latitude and longitude is a pit symbol near the north edge of Section 35, T19N, R3E, on the USGS 7.5-minute Palermo quadrangle. This location represents an approximate center of the large dredge field that extends from the city of Oroville to the vicinity of East Biggs.

Comment (Commodity): Commodity Info: the gold was fine and was present chiefly in the gravels. Fineness ranged from 915 to 930. Minor amounts of platinum were recovered.

Comment (Commodity): Ore Materials: Native gold, native platinum

Comment (Development): The area was settled in 1849. Shallow placers were mined during the gold rush. Bucket-line dredging was introduced here in 1898, the first in California. The field was highly productive from 1903 to 1916; in 1908 there were 35 dredges active. Output later declined, with dredging sporadically active until the 1950?s. The dredge field is now an important source of sand and gravel.

Comment (Economic Factors): Clark (1970) estimated the production of dredging in the district at about 1,964,000 ounces of gold. Dredge recoveries ranged from $0.15 to $0.25 gold per cubic yard at $35/oz.

Comment (Workings): Most mining in this district was accomplished through surface placering and dredging, although there was some underground mining at the city of Oroville. Digging depths ranged from 25 feet upstream to as much as 55 feet downstream. Vast deposits of dredge tailings still remain in this district.

---

References

Reference (Deposit): Doolittle, J.E., 1908, Gold dredging in California: California State Mining Bureau Bulletin 36, p. 68-88.

Reference (Deposit): Clark, W. B., 1970, Gold districts of California: California Divisions of Mines and Geology Bulletin 193, p. 103-104.

Reference (Deposit): Helley, E.J. and Harwood, DS., 1985, Geologic map of the late Cenozoic deposits of the Sacramento Valley and northern Sierra foothills, California: U.S. Geological Survey Miscellaneous Field Studies Map MF-1790, scale 1:62,500.

Reference (Deposit): Lindgren, W., 1911, Tertiary gravels of the Sierra Nevada: U.S. Geological Survey Professional Paper 73, p. 89-90.

Reference (Deposit): Saucedo, G.J. and Wagner, D.L., 1992, Geologic map of the Chico Quadrangle, California: California Department of Conservation, Division of Mines and Geology Regional Geologic Map Series, Map No. 7A, scale 1:250,000.

Reference (Deposit): Unruh, J.R., 1990, Stratigraphy and late Cenozoic deformation in the Oroville area, east-central Sacramento Valley, California: Ph.D. dissertation, University of California, Davis, 305 p.

Reference (Deposit): Winston, W.B., 1910, Gold dredging in California: California State Mining Bureau Bulletin 57, p. 111-158.

---

California Gold

"Where to Find Gold in California" looks at the density of modern placer mining claims along with historical gold mining locations and mining district descriptions to determine areas of high gold discovery potential in California. Read more: Where to Find Gold in California.