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Angels Mine

Past Producer in Calaveras county in California, United States with commodities Gold, Silver
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Public Land Survey System information
  6. Commodities
  7. Materials information
  8. Alteration
  9. Mineral occurrence model information
  10. Host and associated rocks
  11. Nearby scientific data
  12. Geologic structures
  13. Ore body information
  14. Controls for ore emplacement
  15. Economic information about the deposit and operations
  16. Mining district
  17. Land status
  18. Bibliographic references
  19. General comments
  20. Reporter information

Geologic information

Identification information

Deposit ID 10310584
Record type Site
Current site name Angels Mine
Alternate or previous names Big Mine, Southwell Mine

Comments on the site identification

  • The Angels Mine is located is located within the city of Angels Camp in southwestern Calaveras County, California. The gold mines in and around Angels Camp are part of the Angels Camp mining district, which is credited with producing at least $30 million in gold (Clark, 1970). The Angels Mine alone is thought to have produced in excess of $3.25 million from rich oxidized surface ores, massive free-milling gold-quartz veins, and disseminated auriferous pyrite within bodies of mineralized schist.

    The Angels Mine, which has also been known as the Big Mine and Southwell Mine, is a consolidation of the Angels, Billings, Crystal, Dr. Hill, Minnie Hennesay, McCormick, Oneida, Potter, and Valentine Jr. claims, comprising a total of 101.15 acres.
    The Angels claim was first worked in the late 1850s. In 1886, the claims were consolidated by the Angels Quartz Mining Company and worked as a unit almost continuously until March 1918 when the mine was idled at a depth of 1,050 feet.

Geographic coordinates

Geographic coordinates: -120.54738, 38.0755 (WGS84)
Elevation 457
Location accuracy 100(meters)
Relative position The Angels Mine is located within the City of Angels Camp

Site location context

Political divisions (FIPS codes)

Calaveras(county)

California(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Angels Camp(quadrangle 1:24,000 scale)

San Andreas(quadrangle 1:100,000 scale)

Sacramento(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Upper Stanislaus(hydrologic unit)

San Joaquin(hydrologic accounting unit)

San Joaquin(hydrologic subregion)

California(hydrologic region)

Geographic areas

Country State County
United States California Calaveras

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 003N 013E 33 NW/4 NE/4 California

Comments on the location information

  • Location selected for latitude and longitude is the Angels Mine shaft symbol on the USGS 7.5 minute Angels Camp quadrangle

Commodities

Commodity Importance
Gold Primary
Silver Secondary

Comments on the commodity information

  • Commodity Info: Usually the gold was in fine particles, although occasional high-grade pockets containing coarse gold were found
  • Ore Materials: Disseminated free gold and auriferous pyrite.
  • Gangue Materials: Quartz, calcite, talc, ankerite, and sericite

Materials information

Materials Type of material
Gold Ore
Pyrite Ore
Quartz Ore
Calcite Ore
Talc Ore
Ankerite Ore
Sericite Ore

Alteration

  • (Local) Ankeritic and sericitic alteration of wall rock with disseminated aurtiferous pyrite mineralization

Mineral occurrence model information

Model code 273
USGS model code 36a
Deposit model name Low-sulfide Au-quartz vein
Mark3 model number 27

Host and associated rocks

  • Host or associated Host
    Rock type Metamorphic Rock > Schist > Amphibole Schist
    Rock unit name Calaveras Complex
    Stratigraphic age (youngest) Mesozoic
    Stratigraphic age (oldest) Paleozoic

Nearby scientific data

(1) -120.54738, 38.0755
ListMap

Economic information

Geologic structures

Type of structure Local
Structure description Melones Fault zone
Type of structure Regional
Structure description Bear Mountains fault zone, Melones fault zone

Ore body information

  • General form Tabular, pinch and swell

Controls for ore emplacement

  • Ore shoots within mesothermal gold-bearing quartz veins.

Comments on the geologic information

  • REGIONAL GEOLOGY

    The Angels Camp district is within the Sierra foothills, where bedrock consists of north trending tectonostratigraphic belts of metamorphosed sedimentary, volcanic, and intrusive rocks that range in age from late Paleozoic to Mesozoic. The structural belts, which extend about 235 miles along the western side of the Sierra, are flanked to the east by the Sierra Nevada Batholith and to the west by sedimentary rocks of the Cretaceous and Jurassic Great Valley sequence. The structural belts are internally bounded by the Melones and Bear Mountains fault zones and are characterized by extensive faulting, shearing, and folding (Earhart, 1988).

    From El Dorado County southward into Tuolumne County, lode gold deposits occur in three distinct lithologic belts - the West Gold Belt, the Mother Lode Belt, and the East Gold Belt. The Mother Lode Belt is responsible for most of the gold produced. However, there has also been substantial gold production from the West Belt and East Belt.

    The West Belt consists of widely scattered gold deposits located west of the Mother Lode vein system. Gold occurs in irregular quartz veins and stringers in schist, slate, granitic rocks, altered mafic rocks, and as gray ore in greenstone. The West Belt can be divided into an eastern component composed of an ophiolitic melange and a western component composed of Jurassic rocks of the Copper Hill volcanics, Salt Springs slate, and Gopher Ridge volcanics. The Bear Mountains fault zone separates the melange from the Copper Hill volcanics.

    The Mother Lode Belt traverses western Calaveras County and consists of the upper Jurassic Logtown Ridge and upper Jurassic Mariposa formations. The Logtown Ridge Formation consists of about 6,500 feet of volcanic and volcanic-sedimentary rocks of island arc affinity. These rocks are mostly basaltic and include flows, breccias, and a variety of layered pyroclastic rocks. The overlying Mariposa Formation contains a distal turbidite, hemipelagic sequence of black slate, schist, amphibolite and chlorite schist, fine grained tuffaceous rocks, and subvolcanic intrusive rocks. The thickness of the Mariposa Formation is difficult to ascertain due to structural complexities, but is estimated to be about 2,600 feet thick at the Consumnes River (Earhart, 1988).

    Mother Lode 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, 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.
  • Wall rocks have invariably been hydrothermally altered, having been partially to completely converted to ankerite, sericite, quartz, pyrite, arsenopyrite, chlorite, and albite with traces of rutile and leucoxene (Knopf, 1929). The mineralization is usually adjacent to the veins in ground that has been fractured and contains small stringers and lenses of quartz. Locally, greenstone bodies adjacent to the quartz veins contain enough disseminated auriferous pyrite in large enough bodies to constitute what has been called "gray ore". Altered slate wall rock commonly contains pyrite, arsenopyrite, quartz, chlorite, and sericite with or without ankerite (Zimmerman, 1983).

    Large bodies of mineralized schist also form low-grade ore bodies throughout the Mother Lode. This ore consists of amphibolite schist that has been subjected to the same processes of alteration, replacement, and deposition that formed the greenstone gray ores. The altered schist consists mainly of ankerite, sericite, chlorite, quartz, and albite. Gold is associated with the pyrite and other sulfides that are present. Pyrite comprises about 8 percent of the rock. The average grade of mineralized schist is about 0.1 oz per ton.

    The Melones Fault zone separates the Mother Lode Belt from the East Belt. The Eastern Belt is dominantly argillite, phyllite and phyllonite, chert, and metavolcanic rocks of Paleozoic-Mesozoic age. The phyllite and phyllonite are dark to silvery gray. The chert is mostly thin bedded with phyllite partings. The Paleozoic-Mesozoic metasedimentary and metavolcanic rocks of the Eastern Belt have been assigned to the Calaveras Complex by most investigators (Earhart, 1988). Older Paleozoic metamorphic rocks have been assigned to the Shoo Fly Complex. The metamorphic complexes have are intruded in places by Mesozoic plutonic rocks.

    Lode deposits of the East Belt consist of many individual gold-bearing quartz veins enclosed in metamorphic rocks of possible Jurassic age, metamorphic rocks of the Calaveras Complex, metamorphic rocks of the Shoo Fly complex, or in granitic rocks. Most of the veins trend northward and dip steeply. An east-west set of intersecting faults may be a controlling factor in controlling deposition of ore. Ore deposits of the East Belt are smaller and narrower than those of the Mother Lode, but commonly are more chemically complex, and richer in grade. Gold is usually associated with appreciable amounts of pyrite, chalcopyrite, pyrrhotite, galena, sphalerite, and arsenopyrite.

    LOCAL GEOLOGY

    The geology of the Angels Camp district is complex. Bedrock, which is assigned either to the Calaveras Complex or unnamed units of Jurassic age, consists of a series of northwest-striking beds of amphibolite and chlorite schists, phyllite, greenstone, and metagabbro. Ore deposits occur either in amphibolite and chlorite schist or phyllite. There are three principal northwest-striking vein systems in the district. In the westernmost system, the veins are in phyllite. In the center system, the veins are along the western margin of a northwest-trending belt of metagabbro. In the eastern system, which includes the Angels Mine, the ore deposits occur in amphibolite and greenstone. To the east and west of the district, bedrock is composed of slate, impure quartzite, and micaceous schist (Clark, 1970).

    Ore deposits consist of massive quartz veins, zones of parallel quartz stringers, and bodies of mineralized amphibolirte schist.
  • The Angels Mine claims contain a number of quartz veins, but two principal quartz veins were developed, the "East" vein and the "West," or "Mother Lode," vein, both striking northwest - southeast. The East vein dips 80? NE, and the West vein dips 65? NE. Both veins averaged 20 feet wide. Stope lengths ranged from 100-200 feet. The ore contained disseminated free gold and auriferous pyrite. Usually the gold was in fine particles, although occasional high-grade pockets containing coarse gold were found. Calcite, talc, ankerite and sericite are commonly present in the ore (Clark, 1970).

    The value of the ore during the last years of the operation ranged form $2 - $10 per ton and the concentrates ranged from $38 to $70 per ton at the old gold price of $20 (Clark and Lydon, 1962).

Economic information about the deposit and operations

Operation type Underground
Development status Past Producer
Commodity type Metallic
Deposit size Small
Significant Yes
Discovery year 1850

Mining district

District name Angels Camp

Land status

Ownership category Private
Area name City of Angels Camp

Comments on the workings information

  • The main working entry of the Angels Mine was the 850-foot, 3-compartment Angels shaft, with levels at 100, 200, 400, 500, 700, and 850 feet. From the 850-foot level, a winze was sunk to the 1,050-foot level, and an 800-foot crosscut was driven east. The 800-foot Crystal shaft was located to the southwest and had levels at 100, 200, 400, 500, and 600 feet. The Crystal shaft was used primarily for lowering timbers (Tucker, 1914).

    During its final years of operation, ore was mined on the 200-, 400-, and 500-foot levels. Ore was hoisted by a double drum electric hoist, and dumped into storage bins in 60-foot gallows frame, passing over a grizzly to a 10" x 20" Blake crusher. Ore was then trammed from the storage bins at the shaft to the mill up a 30? incline (Tucker, 1914).

    The mill, which treated about 200 tons of ore per day, was equipped with 40 stamps. Battery pulp was concentrated on sixteen 4-foot Frue vanners. An extraction of 90% was obtained in the mill (Clark and Lydon, 1962). Concentrates ran from $38 to $70 per ton, averaging about $50 per ton.

Comments on other economic factors

  • The Angels Mine alone is thought to have produced in excess of $3.25 million. The value of the ore during the last years of the operation ranged form $2 - $10 per ton and the concentrates ranged from $38 to $70 per ton at the old gold price of $20 (Clark and Lydon, 1962).

Comments on development

  • The Angels claim was first worked in the late 1850s and by 1872 was developed by a 600-foot shaft and equipped with a 30-stamp mill. Prior to their consolidation with the Angels claim in 1886, the Dr. Hill claim had yielded $250,000 by 1867. In 1882, the Potter claim was being worked through a 100-foot shaft. In 1886, the claims were consolidated by the Angels Quartz Mining Company and worked as a unit almost continuously until March 1918. A $100,000 pocket was reported to have been discovered on the Crystal claim in 1910. The total output of the property is unknown, but public figures show its value exceeds $3.25 million (Clark and Lydon, 1962).

    The mine was closed on March 1, 1918 on account of the owner's death. At the time of the closing, the deepest level was 1050 feet, and ore was being mined on the 200, 400, and 500-foot levels (Logan, 1921).

Reference information

Bibliographic references

  • Deposit

    Brown, J.A., 1890, Calaveras County, Angels Mine, California State Mining Bureau, 10th Annual Rport of the State Mineralogist, p. 151.

  • Deposit

    Clark, L.D., 1970, Geology of the San Andreas 15-minute quadrangle, Calaveras County, California: California Division of Mines and Geology Bulletin 195, 23 p.

  • Deposit

    Clark, W. B., 1970, Gold districts of California: California Divisions of Mines and Geology Bulletin 193, p. 25-28.

  • Deposit

    Clark. W. B., and Lydon, P.A., 1962, Mines and mineral resources of Calaveras County, California: California Division of Mines and Geology County Report No. 2, p. 40.

  • Deposit

    Eric, J.H., Stromquist, A.A., and Swinney, C.M., 1955, Geology and mineral deposits of the Angels Camp and Sonora quadrangles, Calaveras and Tuolumne counties, California: California Division of Mines Special Report 41, 55 p.

  • Deposit

    Knopf, A., 1929, The Mother Lode system of California: U. S. Geological Survey Professional Paper 157, 88 p.

  • Deposit

    Logan, C. A., 1921, Calaveras County, Angels Mine: California State Mining Bureau, 17th Report of the State Mineralogist, p. 420.

  • Deposit

    Tucker, W.B., 1914, Calaveras County, Angels Mine: California State Mining Bureau, 14th Annual Report of the State Mineralogist, p. 68-69.

  • Deposit

    Zimmerman, J.E., 1983, The Geology and structural evolution of a portion of the Mother Lode Belt, Amador County, California: unpublished M.S. thesis, University of Arizona, 138 p.

General comments

Subject category Comment text
Deposit The Angels Mine produced over $3.25 million from quartz veins, zones of parallel quartz stringers, and bodies of mineralized amphibolirte schist. The two principal veins, the "East" vein and the "West" or "Mother Lode" vein, averaged 20 feet wide. The ore contained disseminated free gold and auriferous pyrite. Usually the gold was in fine particles, although occasional high-grade pockets containing coarse gold were found. Calcite, talc, ankerite and sericite are commonly present in the ore (Clark, 1970).

The value of the ore during the last years of the operation ranged form $2 - $10 per ton and the concentrates ranged from $38 to $70 per ton at the old gold price of $20 (Clark and Lydon, 1962).

Reporter information

Type Date Name Affiliation Comment
Reporter 10-MAY-2006 Downey, Cameron (Higgins, Chris, T.) California Geological Survey CGS (Formerly CDMG)
Editor 01-SEP-2007 Schruben, Paul G. U.S. Geological Survey Converted from S&A FileMaker format to Oracle. Edit checks on rocks, units, and ages with Geolex search, and other fields.

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

External references

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Authoritative California resources

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