Lincoln (Garden Bar)

Site Name

Primary: Lincoln (Garden Bar)

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Commodity

Primary: Gold
Secondary: Platinum
Secondary: Silver

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Location

State: California
County: Placer
District: Lincoln

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Land Status

Land ownership: Private
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.
Administrative Organization: Placer County Planning Dept.

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Holdings

Not available

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Workings

Not available

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Ownership

Not available

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Production

Not available

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Deposit

Record Type: District
Operation Category: Past Producer
Deposit Type: Stream placer
Operation Type: Surface
Years of Production:
Organization:
Significant: Y

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Physiography

Not available

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Mineral Deposit Model

Model Name: Placer Au-PGE

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Orebody

Form: Irregular

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Structure

Type: R
Description: Bear Mountain Fault Zone

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Alterations

Not available

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Rocks

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

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Analytical Data

Not available

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Materials

Ore: Gold
Gangue: Chlorite
Gangue: Epidote
Gangue: Amphibole
Gangue: Pyrite
Gangue: Zircon
Gangue: Ilmenite
Gangue: Magnetite
Gangue: Quartz
Gangue: Siderite

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Comments

Comment (Workings): Mining operations in the Lincoln district were conducted using draglines and dragline dredges. Most draglines used 50 to 60 foot booms and buckets of 1 to 1.5 cubic yard capacity. Generally, the dredged gravels were run through a grizzly or revolving screen with the finer sands and gravels then being run through sluices. Detailed accounts of several dragline and processing operations in the district during 1935 are given by Logan (1936).

Comment (Identification): The Lincoln (Garden Bar) District is in western Placer County about 15 miles west of Auburn. Mining in the district consisted of dragline dredging of Quaternary auriferous gravel deposits within lower Auburn Ravine and Doty Ravine, which are about two miles northeast and four miles north of Lincoln, respectively. Most mining occurred during the 1930s. A total of approximately 1,200 acres were dredged. While very little information is available about the mining operations, and total production is unknown, some accounts suggest the Lincoln District was the most profitable dragline dredge field in the state (Clark, 1970).

Comment (Location): Location selected for latitude and longitude is the approximate center of the lowermost dredge tailings in lower Auburn Ravine (C SW/4 Sec. 12-T12N-R6E)

Comment (Development): Placer gold was first discovered in Quaternary gravels in the American River at Coloma in 1848. This discovery, in the race at Sutter's Mill touched off the California Gold Rush. Shortly thereafter, prospectors discovered placer gold, both in the active channels of the rivers of the Northern Sierra Nevada and in the widespread alluvial gravels deposited in floodplains and terraces at the mouths of the river canyons. Small-scale placer mining of the terrace gravels at the mouths of the Feather, Yuba, and American rivers occurred as early as 1849, but large-scale mining did not take place until the 1890s and early 1900s with the introduction of bucket-line dredging. Dredging operations at most of the larger deposits continued until the mid 1950s and 1960s. While it is known that small-scale placer mining occurred during the early part of the gold rush near the town of Auburn in the upper reaches of Auburn Ravine, it is unclear when the lower deposits in the Lincoln District were discovered. There is also very little information about their exploitation until the onset of dragline dredging in the district in 1935. During that year, at least five companies were operating draglines or bucket dredges on leases at the mouth of Auburn and Doty ravines. Accounts of these operations during 1935 are given by Logan (1936). No information is readily available regarding later operations or the duration of the operations. It is surmised that some level of operations continued until the 1950s as was the case in neighboring dredging districts. Approximately 1200 acres were dredged.

Comment (Economic Factors): Little information is available regarding gold production for individual operations or the district as a whole. Clark (1970) reported that recoveries ranged from $0.16 to $0.60 per yard and that the Lincoln deposits were probably the most profitable dragline dredge fields in the state.

Comment (Geology): The northern Sierra Nevada is home to numerous important placer gold deposits. While most noteworthy deposits consist of remnant auriferous Tertiary gravel deposits laid down by the ancestral Yuba, American, Mokelumne, Calaveras, Stanislaus, and Tuolumne rivers in the foothills of the Sierra Nevada, several auriferous Quaternary gravel deposits were also deposited along the western edge of the Sierra by Pleistocene and younger rivers and streams. Some of the more important deposits are those of the Lincoln, Folsom, Oroville, Hammonton, and Michigan Bar districts. Geologically the Lincoln District is located along the western edge of the Sierra Nevada where Cretaceous and younger rocks of the Great Valley of California rest on basement rocks of the Northern Sierra Nevada western lithotectonic belt. Throughout most of the district, thin Quaternary alluvial and shoreline gravels onlap exposed Mesozoic dioritic igneous rocks of the Penryn Pluton or exposed metamorphosed intermediate to mafic rocks of the Copper Hill volcanics. Underlying bedrock at most dredge sites is soft weathered tuff or weathered granodiorite. In most of the dredged areas the gravels are thin, range from 5 to 20 feet thick, and pinch out rapidly to the east. In some areas, the gravel occurs in irregular and isolated patches. The coarsest material is generally cobbles no more than a few inches in diameter. Some of the finer gravels are thought to be redistributed shoreline gravels, with the bulk of the deposits being alluvial gravels of modern streams. The source of the gold is from the reworking of auriferous Tertiary gravel deposits and erosion of bedrock gold-quartz veins in the foothills of the Sierra Nevada. The gravel was transported by westerly flowing streams within Auburn and Doty ravines. The bulk of the gold is likely from the quartz veins of the important Ophir mining district located approximately 8 miles up Auburn Ravine. This is supported by the presence of abundant quartz gravel that assays have shown contain enough gold to suggest a gold-quartz vein origin.

Comment (Commodity): Ore Materials: Native gold - Fine to coarse gold and nuggets (.915-.935 fine)

Comment (Commodity): Gangue Materials: Quartz and metamorphic gravels; accessory minerals magnetite, ilmenite, zircon, pyrite, amphibole, epidote, chlorite, and siderite

Comment (Deposit): The Lincoln (Garden Bar) deposits consist of thin (5-20 feet thick) auriferous Quaternary shoreline and alluvial sands and gravels deposited by Pleistocene to recent streams in the lower reaches and at the mouths of Auburn Ravine and Doty Ravine near Lincoln. The gravels were derived from the reworking and erosion of older Tertiary auriferous gravel deposits and erosion of bedrock gold-quartz veins in the Sierra Nevada Foothills. The quartz veins of the Ophir lode-gold district are considered a major source because of its location 8 miles upstream in Auburn Ravine and the abundance of quartz detritus that contains a measurable gold content.

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References

Reference (Deposit): Clark, W.B., 1970, Gold districts of California: California Division of Mines and Geology Bulletin 193, p. 87.

Reference (Deposit): Lindgren, W., 1894, Sacramento folio, California: U.S. Geological Survey Atlas of the U.S., Folio 5, 3 p.

Reference (Deposit): Logan, C.A., 1936, Gold mines of Placer County: California Journal of Mines and Geology, v. 32, p. 80-83.

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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.