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Utica Mine (Brown Mine; Brown claim; Little Nugget claim; Washington claim; Utica claim; Confidence claim; Stickle claim; Raspberry claim; Dead Horse claim; Jackson claim), Angels Camp, Angels Camp Mining District, Calaveras County, California, USAi
Regional Level Types
Utica Mine (Brown Mine; Brown claim; Little Nugget claim; Washington claim; Utica claim; Confidence claim; Stickle claim; Raspberry claim; Dead Horse claim; Jackson claim)Mine (Inactive)
Angels Camp- not defined -
Angels Camp Mining DistrictMining District
Calaveras CountyCounty
CaliforniaState
USACountry

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Latitude & Longitude (WGS84):
38° 4' 13'' North , 120° 32' 18'' West
Latitude & Longitude (decimal):
Type:
Mine (Inactive) - last checked 2020
Nearest Settlements:
PlacePopulationDistance
Angels Camp2,677 (2012)0.3km
Vallecito442 (2011)6.1km
Murphys2,213 (2015)10.1km
Tuttletown668 (2011)11.1km
Columbia2,297 (2017)12.6km
Nearest Clubs:
Local clubs are the best way to get access to collecting localities
ClubLocationDistance
Calaveras Gem & Mineral SocietyAngels Camp, California0km
Amador County Gem & Mineral SocietySutter Creek, California43km
Mindat Locality ID:
74954
Long-form identifier:
mindat:1:2:74954:6
GUID (UUID V4):
eeb1e873-f472-4184-b7a2-d5e3c98d07ec


A former Au-Cu mine located in secs. 33 & 34, T3N, R13E, MDM, 0.2 km (700 feet) N of Angels Camp proper. Discovered before 1850. MRDS database stated accuracy for this location is 100 meters.

The Utica Mine is one on the best-known gold mines in the Mother Lode, and is the consolidation of the Brown, Confidence, Dead Horse, Jackson, Little Nugget, Raspberry, Stickle, Utica, and Washington claims. The surface of the Utica claim was mined during the early part of the gold rush, but large-scale development was only conducted between 1893 and 1915 by the Utica Gold Mining Company. During the 1890s, the Utica Mine was one of the most productive in the nation - the output from January 1893 to September 1895 was $4,154,026 (Logan, 1934). The Utica Mine alone is thought to have produced in excess of $17 million at the old price of gold.

The surface of the Utica claim was mined during the early part of the gold rush, and the ore was treated in arrastras. The Stickle claim was active during the 1860s. In 1871, it had been developed to a depth of 240 feet and was equipped with a 10-stamp mill. The Confidence claim was active in the 1880s, and its ore was treated in a five-stamp mill (Clark and Lydon, 1962).

Later, C.D. Lane gained control of the Utica claim. Hobart and Hayward, who controlled numerous mines in the area were brought in as partners in the 1880s and shortly thereafter, the Utica Mining Company was organized and large scale development commenced in 1893. The other claims that now constitute the property (Brown, Confidence, Dead Horse, Jackson, Little Nugget, Raspberry, Stickle, and Washington claims) were gradually acquired and the mine was developed on a major scale.

During the 1890s, the Utica Mine was one of the most productive in the nation - the output from January 1893 to September 1895 was $4,154,026 (Logan, 1934). More than 500 men were on the payroll. By 1900, the Cross vertical shaft bottomed at 1312 feet. Operations continued into late 1915 when the mine was shut down. Except for mill cleanups and small amounts of gold recovered from the dump in the 1930s, the mine has been idle since.

McCurdy (1932) attributes the cessation of mining and exploration for the footwall portion of the Utica vein to inferior or obsolete equipment resulting in the overly high operating costs.

Mineralization is a vein deposit (Mineral occurrence model information: Model code: 273; USGS model code: 36a; Deposit model name: Low-sulfide Au-quartz vein; Mark3 model number: 27), hosted in Late Jurassic Calaveras Complex amphibolite schist and chloritic and talcose schist. Lenticular quiartz-calcite veins are separated by various thicknesses of fissured amphibolite, chloritic and talcose schist. The S portion of the mjine is more highly sheared than the N portion. The ore bodies are a complex network of stringers and mineralized country rock. Stopiong thicknesses varied from 10 to 100 feet. The SDtickles Mine to the S is similar but more sheared and fissile. Most stringers follow the schistosity, but others traverse it in all directions. The westerly lead is 60 to 90 feet thick, the easterly 20 to 30 feet. Brown quartz sometimes forms well-defined stringers and is also intimately associated with country rock and alteration. Stringers dip easterly nearly vertically. High-grade pockets, both ___? and country rocks contain free gold and auriferous pyrite.. The richest ore is "brown quartz," a fine granular aggregate of quartz, dolomite, and sometimes albite, thickly speckled with small crystals of pyrite. Local alteration is ankeritic and sericitic alteration of wall rock with disseminated aurtiferous pyrite mineralization. Local rocks include undivided pre-Cenozoic metavolcanic rocks, unit 2 (undivided).

The ore bodies in the Utica mine are not within simple veins like many Mother Lode deposits, but instead consist of numerous lenticular quartz-calcite stringer veins separated by various thicknesses of mineralized fissured mineralized amphibolite and chloritic and talcose schist. Nonetheless, the mineralized zone was designated the Utica vein (Bonanza vein in some records) in most mine records. The stringers are largely quartz, but carbonate is abundant, especially in the smaller fissures. The stringers strike about N 50? W and dip about 70-80? northeasterly, lying nearly in the planes of schistosity of the country rock (Eisenhauer, 1932). Both the quartz and nearby country rock contain free gold and auriferous pyrite. In the south portion of the mine the country rock is more highly sheared than in the north, and the ore bodies were more complex networks of stringers and mineralized country rock (Clark and Lydon, 1962). In the Stickle claim on the south side of the Utica Mine property, the ore body is separated into two longitudinal portions, by a horse of barren schist and stringers 30 to 50 feet wide. The westerly portion is the more important being from 60-90 feet wide, while the eastern part is only 20 or 30 feet wide.

The richest ore was called "brown quartz", consisting of a fine granular aggregate of quartz, dolomite, and sometimes albite, with abundant small crystals of pyrite. The brown quartz does not always form well-defined veins or stringers, but is intimately associated with the country rock, and is in part an altered form of the country rock. The other vein minerals are free gold, sericite, and chalcopyrite. Gold is not visible in most of the ore, but occurs in considerable masses in certain rich streaks (Ramsome, 1900).

The grade of ore varied greatly. During the first year's operation in 1894, the shallowest ores yielded as much as $13.02 per ton but declined to $3.60 or less per ton in following years. Occasionally small high-grade pockets were found. The stringers dip easterly but are nearly vertical. Pyrite and chalcopyrite are the only sulfides reported in the ore (Clark and Lydon, 1962). Ore averaged about 2% concentrates.

The neighboring Gold Cliff Mine (also operated by the Utica Gold Mining Company) developed the Gold Cliff vein, a parallel deposit very similar to the Utica vein. The Gold Cliff vein system dips about 40? northeasterly and converges with the Utica vein on the 2700-foot level of the Utica Mine.

Some mine accounts indicate that the junction of the Utica and Gold Cliff veins was prospected and found not to contain a large ore body as was originally expected. Other accounts and geological reports (McCurdy, 1932; Eisenhauer, 1932) indicate that the Utica vein system ends abruptly at a 150-foot thick, northeasterly dipping talc zone at the 800-foot level in the Stickle shaft. Elsewhere in the mine the equivalent talc zone occurred only as small "dislocated bunches" (Eisenhauer, 1932). Due to differences in the strike and dip of the Utica vein and talc zone, the bottom of the vein system gets progressively deeper from northwest to southeast. In the neighboring Lightner Mine (to the northwest), the talc zone also floored the ore body between the 500 and 600 foot levels. Geological interpretation in the lower workings and below the talc zone are sketchy and hampered by the lack of geological record keeping in the shallower zones by the Utica Gold Mining Company (Eisenhauer 1932). However, Eisenhauer (1932) and McCurdy (1932) interpret the thin talc zone to be a reverse fault plane above which the best ore occurred in the hanging wall.
Very little exploration was conducted below the talc zone to locate the Utica vein ore body on the footwall of the fault (Eisenhauer 1932). Limited cross cutting below the talc zone failed to locate the footwall portion of the Utica vein (Eisenhauer 1932). Eisenhauer (1932) notes that miners intimately familiar with the characteristics of the Utica vein ore described the ore below the talc zone as a stringer lead distinctly different in appearance and lower-grade from the brown quartz ore developed above the talc.

Geologic structures: Regional: Bear Mountains fault zone, Melones fault zone; local: Melones Fault Zone.

Workings include surface and underground openings with an overall depth of 929.64 meters and an overall length of 1,869.95 meters. The main shafts are 1,470 and 2,100 foot Cross, 1,000 foot Stickle, and the N and S Utica shafts. Thousands of feet of winzes, levels and crosscuts were driven. 900 feet NW of the Cross shaft a vertical winze was sunk to the 2,850 foot level with a 300 foot crosscut and anotehr winze to the 3,050 foot level.

The Utica Mine was originally developed through he Utica North and Utica South Shafts until 1902, after which the 1470-foot vertical Cross shaft and the 1000-foot vertical Stickle shaft (650 feet to the northwest) became the main working entries. The Cross shaft was sunk in hard rock to provide a permanent opening prior to abandoning the Utica North and Utica South shafts which had been used to mine the upper portions of the Utica vein. Working levels in Cross and Stickle shafts were turned every 100 feet. About 960 feet northwest of the Cross shaft, on the 1400-foot level, a hoist station was cut and a winze was sunk to the 2850-foot level. On this level, a crosscut extended 300 feet to the northeast where an inclined winze extended to the lowest 3050-foot level were the latest work was done before the mine shut down in 1915.
From the 1500-foot level a southwest crosscut is connected with the 1400-foot level of the neighboring Gold Cliff Mine. Details of mine workings are sketchy, but there are though to be over 100 miles of underground workings, a portion of which are shown by Clark and Lydon (1962, p. 73).

Stoping operations on the Utica vein system were confined to between the surface and the 13th level (1700 feet) (Eisenhauer 1932). Stoping widths ranged from 10 to 100 feet. Square set stopes with waster filling and open stopes with pillars were the preferred mining methods (Clark and Lyndon, 1962).

During the 1890s, ore was treated in a 120-stamp mill. Storms (1900) detail the processes of ore milling and processing at the turn of the century. In later operations, the ore was treated in a 300-ton mill equipped with 60 stamps and 36 Frue vanners (Clark and Lydon, 1962). Mine dumps are conspicuously absent since all waste rock was utilized underground as backfill.

Production data are found in: Clark (1962).

The Utica Mine is credited with a toal production of $17,000,000 of Au (period values). The Stickle claim was active in the 1860's. From 1893 to 1895, Utica output was $4,154,026 (period values). The mine has been idle since 1915, except for dump cleanups in the 1930's. The bulk of the production came from above the 1,300 foot level. Shallow ores yielded as much as $13.02 per ton but declined to $3.60 or less (period values) in the deeper levels.

Select Mineral List Type

Standard Detailed Gallery Strunz Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.


Mineral List


10 valid minerals.

Detailed Mineral List:

Albite
Formula: Na(AlSi3O8)
Calcite
Formula: CaCO3
Chalcopyrite
Formula: CuFeS2
'Chlorite Group'
Dolomite
Formula: CaMg(CO3)2
Gold
Formula: Au
Gypsum
Formula: CaSO4 · 2H2O
Description: Occurs as platy aggregates with quartz.
Muscovite
Formula: KAl2(AlSi3O10)(OH)2
Muscovite var. Sericite
Formula: KAl2(AlSi3O10)(OH)2
Pyrite
Formula: FeS2
Quartz
Formula: SiO2
Talc
Formula: Mg3Si4O10(OH)2

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
Gold1.AA.05Au
Group 2 - Sulphides and Sulfosalts
Chalcopyrite2.CB.10aCuFeS2
Pyrite2.EB.05aFeS2
Group 4 - Oxides and Hydroxides
Quartz4.DA.05SiO2
Group 5 - Nitrates and Carbonates
Calcite5.AB.05CaCO3
Dolomite5.AB.10CaMg(CO3)2
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
Gypsum7.CD.40CaSO4 · 2H2O
Group 9 - Silicates
Talc9.EC.05Mg3Si4O10(OH)2
Muscovite9.EC.15KAl2(AlSi3O10)(OH)2
var. Sericite9.EC.15KAl2(AlSi3O10)(OH)2
Albite9.FA.35Na(AlSi3O8)
Unclassified
'Chlorite Group'-

List of minerals for each chemical element

HHydrogen
H GypsumCaSO4 · 2H2O
H MuscoviteKAl2(AlSi3O10)(OH)2
H TalcMg3Si4O10(OH)2
H Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
CCarbon
C CalciteCaCO3
C DolomiteCaMg(CO3)2
OOxygen
O AlbiteNa(AlSi3O8)
O CalciteCaCO3
O DolomiteCaMg(CO3)2
O GypsumCaSO4 · 2H2O
O MuscoviteKAl2(AlSi3O10)(OH)2
O QuartzSiO2
O TalcMg3Si4O10(OH)2
O Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
NaSodium
Na AlbiteNa(AlSi3O8)
MgMagnesium
Mg DolomiteCaMg(CO3)2
Mg TalcMg3Si4O10(OH)2
AlAluminium
Al AlbiteNa(AlSi3O8)
Al MuscoviteKAl2(AlSi3O10)(OH)2
Al Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
SiSilicon
Si AlbiteNa(AlSi3O8)
Si MuscoviteKAl2(AlSi3O10)(OH)2
Si QuartzSiO2
Si TalcMg3Si4O10(OH)2
Si Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
SSulfur
S ChalcopyriteCuFeS2
S GypsumCaSO4 · 2H2O
S PyriteFeS2
KPotassium
K MuscoviteKAl2(AlSi3O10)(OH)2
K Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
CaCalcium
Ca CalciteCaCO3
Ca DolomiteCaMg(CO3)2
Ca GypsumCaSO4 · 2H2O
FeIron
Fe ChalcopyriteCuFeS2
Fe PyriteFeS2
CuCopper
Cu ChalcopyriteCuFeS2
AuGold
Au GoldAu

Other Databases

Link to USGS MRDS:10102731

Other Regions, Features and Areas containing this locality

North America PlateTectonic Plate
USA

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References

 
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