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Michigan Bar Mining District, Sacramento Co., California, USAi
Regional Level Types
Michigan Bar Mining DistrictMining District
Sacramento Co.County
CaliforniaState
USACountry

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Latitude & Longitude (WGS84):
38° North , 121° West (est.)
Estimate based on other nearby localities or region boundaries.
Margin of Error:
~64km
Locality type:


A placer Au-PGE mining district on the lower Cosumnes River around sec. 36, T8N, R8E, MDM.

The Michigan Bar District is a placer-mining locality in and near the Cosumnes River. Mining activity was conducted at several sites between the former settlement of Michigan Bar on the northeast and several miles west and southwest of Bridge House to the area of Sloughhouse.

Location selected for latitude and longitude is the former townsite of Michigan Bar on the USGS 7.5-minute Carbondale quadrangle. Sites of mining, however, extended over various individual locations to the west and south of this location.

Mineralization is a placer Au-PGE deposit (Model code 119; USGS model code 39a; BC deposit profile C01. C02; Deposit model name: Placer Au-PGE; Mark3 model number 54), hosted in Eocene and Quaternary sand and gravels. Ore Materials: Native gold, native platinum. Ore control was mechanical accumulations within stream-channel lag gravels, bars, and point-bar deposits. Local rocks include Jurassic marine rocks, unit 1 (Western Sierra Nevada and Western Klamath Mountains).

Gangue Materials: Metamorphic rock, igneous rock, quartz (all as clasts).

β€’REGIONAL GEOLOGY The Michigan Bar District is situated within the Great Valley geologic province, which is here represented by the Sacramento Valley. It is adjacent to the westernmost edge of the Sierra Nevada geologic province. The Great Valley province is characterized by Cenozoic sedimentary and volcanic rocks, while the Sierra Nevada province is characterized by complex lithologies and structures that were assembled through various plate-tectonic processes. In this region, the Sierra Nevada province is composed of belts of Paleozoic-Mesozoic metamorphic complexes that are intruded by various Mesozoic plutons. Together, they compose the basement of the province. This basement is overlain at higher elevations 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 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. The rocks of the Great Valley province overlie the basement of the Sierra Nevada where it extends westward underneath the San Joaquin Valley.

Local geology: The Michigan Bar District is associated with Cenozoic alluvial deposits of the main drainage of the Cosumnes 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 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 Cenozoic placer deposits along the Cosumnes River at Michigan Bar and farther downstream toward Sloughhouse. Platinum was probably derived from erosion of ultramafic rocks and serpentinite in the Sierra Nevada basement.

Workings included all of the standard placer-mining processes were used in this district including surface, hydraulic, drift, and dredging. Areas of dredge tailings are present locally throughout the district.

Auriferous gravels of the Ione Formation in the Michigan Bar area were hydraulicked extensively in the 1860's and 1870's, and also exploited in a small way by drift mining. The modern alluvial deposits along the Cosumnes River and some of the older bench gravels adjacent to it, including the Ione Formation, were dredged from before the 1920's to the 1950's.

Commodity Info: In 1938, a dragline operation dredged 3,411,337 cubic yards of gravel, which yielded 10,018 ounces of gold. In 1948, another operation dredged about 160,000 cubic yards of gravel, which yielded 655 ounces of gold and 66 ounces of silver.

Production data: Clark (1970) estimated that total production of gold for this district was at least 1,700,000 ounces.

Select Mineral List Type

Standard Detailed Gallery Strunz Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded from this region.


Mineral List

Mineral list contains entries from the region specified including sub-localities

6 valid minerals.

Detailed Mineral List:

β“˜ Galena
Formula: PbS
Reference: Hanks, Henry Garber (1884), Fourth report of the State Mineralogist: California Mining Bureau. Report 4, 410 pp. (includes catalog of minerals of California pp. 63-410), and miscellaneous observations on mineral products): 181; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 191.
β“˜ Gold
Formula: Au
Description: Placer gold.
Reference: Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 30.
β“˜ Kaolinite
Formula: Al2(Si2O5)(OH)4
Colour: White
Description: Occurs in the Eocene Ione Formation.
Reference: Carlson, D.W. (1955), Sacramento County placer mines and gold dredging: California Journal of Mines and Geology: 51: 125-128; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 438.
β“˜ Platinum
Formula: Pt
Description: Placer material that averages 44.75% Pt, 24.84% Ir, 21.72% Os, and 8.69% Ru.
Reference: Logan, Clarence August (1918), Platinum and allied metals in California: California Mining Bureau. Bulletin 85, 120 pp.: 30-31, 109; Mertie, J.B. (1969) Economic geology of the platinum metals. USGS Professional Paper 630, 120 pp.: 94; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 43; Clark, Wm. B. (1970b) Platinum: California Division Mines and Geology Mineral Information Service: 23(6): 115-123.
β“˜ Pyrite
Formula: FeS2
Reference: Hanks, Henry Garber (1884), Fourth report of the State Mineralogist: California Mining Bureau. Report 4, 410 pp. (includes catalog of minerals of California pp. 63-410), and miscellaneous observations on mineral products): 181; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 191.
β“˜ Sphalerite
Formula: ZnS
Reference: Hanks, Henry Garber (1884), Fourth report of the State Mineralogist: California Mining Bureau. Report 4, 410 pp. (includes catalog of minerals of California pp. 63-410), and miscellaneous observations on mineral products): 181; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 191.

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
β“˜Gold1.AA.05Au
β“˜Platinum1.AF.10Pt
Group 2 - Sulphides and Sulfosalts
β“˜Galena2.CD.10PbS
β“˜Pyrite2.EB.05aFeS2
β“˜Sphalerite2.CB.05aZnS
Group 9 - Silicates
β“˜Kaolinite9.ED.05Al2(Si2O5)(OH)4

List of minerals for each chemical element

HHydrogen
Hβ“˜ KaoliniteAl2(Si2O5)(OH)4
OOxygen
Oβ“˜ KaoliniteAl2(Si2O5)(OH)4
AlAluminium
Alβ“˜ KaoliniteAl2(Si2O5)(OH)4
SiSilicon
Siβ“˜ KaoliniteAl2(Si2O5)(OH)4
SSulfur
Sβ“˜ GalenaPbS
Sβ“˜ SphaleriteZnS
Sβ“˜ PyriteFeS2
FeIron
Feβ“˜ PyriteFeS2
ZnZinc
Znβ“˜ SphaleriteZnS
PtPlatinum
Ptβ“˜ PlatinumPt
AuGold
Auβ“˜ GoldAu
PbLead
Pbβ“˜ GalenaPbS

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Logan, C. A. (1918), Platinum and allied metals in California: California State Mining Bureau Bulletin 85, 120 p.
Carlson, D. W. (1955), Mines and mineral resources of Sacramento County, California: California Journal of Mines and Geology (Report 51): 51(2): 134-143.
Koschmann, A. H., and Bergendahl, M. H. (1968), Principal gold-producing districts of the United States: USGS Professional Paper 610, 283 p.
Clark, W. B. (1970a), Gold districts of California: California Divisions of Mines and Geology Bulletin 193: 90.
Wagner, D. L. and others (1981), Geologic map of the Sacramento Quadrangle, California: California Department of Conservation, Division of Mines and Geology Regional Geologic Map Series, Map No. 1A, scale 1:250,000.
Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 30, 43.
USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10310648.

Other Databases

Link to USGS MRDS:10310648

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