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Mother Lode Belt, Tuolumne Co., California, USA

Latitude: 37°58'37"N
Longitude: 120°28'0"W
The Mother Lode gold belt carries the most productive and best-known mining districts in California's gold country. Although the entire foothill region of the Sierra Nevada is sometimes loosely termed the "Mother Lode Country," technically the Mother Lode is a 120-mile-Iong system of linked or en echelon gold-quartz veins and mineralized schist and greenstone that extends from the town of Mariposa, north and

Map of California gold belts
northwest to northern El Dorado County.


The most productive portion of the Mother Lode has been the 1 mile segment between Plymouth and Jackson in Amador County. Other major sources of gold in the Mother Lode have been the Angels Camp, Bagby, Carson Hill, Coulterville, Georgetown, Greenwood, Jacksonville, Jamestown, Kelsey, Mount Bullion, Nashville, and Placerville districts.

The northwest-trending Mother Lode Belt traverses western Tuolumne County and is associated with the Melones Fault Zone. The rocks of this belt are typically metavolcanic, metasedimentary, and ultramafic, some of which have been hydrothermally altered to assemblages as described below. Mother Lode Belt mineralization is characterized by steeply dipping gold-bearing quartz veins and bodies of mineralized country rock adjacent to veins. Mother Lode veins are characteristically enclosed in Mariposa Formation slate with associated greenstone. The Mother Lode belt vein system ranges from a few hundred feet to a mile or more in width. Within the zone are numerous discontinuous or linked veins, which may be parallel, convergent, or en echelon. The veins commonly pinch and swell. Few can be traced more than a few thousand feet. Mother Lode type veins fill voids created within faults and fracture zones and consist of quartz, gold and associated sulfides, ankerite, calcite, chlorite, limonite, talc, chromium-bearing mica, and sericite. Stringer veins are commonly found in both adjacent footwall and hanging walls. Mother Lode ores are generally low- to moderate-grade (1/3 ounce of gold or less per ton), but ore bodies can be large. Ore shoots are generally short, 200-300 feet being the average stope length. However, they persist at depth, some having been mined to several thousand feet (Clark and Lydon, 1962). Ore shoots are commonly localized at bulges in veins, shear zones, vein intersections, or near abrupt changes in strike or dip.

Mineral List

Mineral list contains entries from the region specified including sub-localities
Acanthite
Albite
Altaite
'Anauxite'
Ankerite
Annabergite
Antigorite
'Asbestos'
Augite
Azurite
Bementite
Beryl
Bornite
Calaverite
Calcite
Chalcopyrite
Chenguodaite
Chlorargyrite
'Chlorite Group'
Choloalite
Chromite
Chrysotile
Cinnabar
Clinochlore
Clinochlore
var: Chromian Clinochlore

Cobaltite
Coloradoite
Cristobalite
Dolomite
var: Ferroan Dolomite
Enstatite
Epidote
Fluorapatite
Galena
Gersdorffite
Goethite
Gold
var: Electrum
Graphite
'Grossular-Hibschite Series'
Hematite
Hessite
'Hornblende'
Ilmenite
Imiterite
Keystoneite
Kuranakhite
Magnesiochromite
Magnesite
Magnetite
Malachite
'Manganese Oxides'
Mcalpineite (TL)
Melonite
Mercury
Millerite
Mimetite
Molybdenite
Muscovite
var: Fuchsite
var: Sericite
'Olivine'
Owyheeite
Petzite
'Phengite
var: Mariposite'

'Pitticite'
'Psilomelane'
'Pumpellyite'
Pyrargyrite
Pyrite
var: Auriferous Pyrite
'Pyroxene Group'
Pyrrhotite
Quartz
Rhodochrosite
Rhodonite
Riebeckite
Rutile
Scorodite
'Serpentine Group'
Siderite
Siegenite
Silver
Skutterudite
Sphalerite
Stilpnomelane
Sylvanite
Talc
Tellurium
Tennantite
Tetradymite
Tetrahedrite
Titanite
Tridymite
Uvarovite
Zoisite


98 entries listed. 77 valid minerals. 1 type locality (valid mineral).

Localities in this Region

USA
USA

The above list contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.

References

Savage, K.S., Tingle, T.N., O'Day, P.A., Waychunas, G.A., and Bird, D.K. (2000) Arsenic speciation in pyrite and secondary weathering phases, Mother Lode gold district, Tuolumne County, California. Applied Geochemistry: 15: 1219-1244.

USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10310603.

External Links


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Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
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