Log InRegister
Home PageAbout MindatThe Mindat ManualHistory of MindatCopyright StatusWho We AreContact UsAdvertise on Mindat
Donate to MindatCorporate SponsorshipSponsor a PageSponsored PagesMindat AdvertisersAdvertise on Mindat
Learning CenterWhat is a mineral?The most common minerals on earthInformation for EducatorsMindat ArticlesThe ElementsBooks & Magazines
Minerals by PropertiesMinerals by ChemistryAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
Mining CompaniesStatisticsUsersMineral MuseumsMineral Shows & EventsThe Mindat DirectoryDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day GalleryMineral Photography

Ophir Mining District (Auburn Mining District; Duncan Hill Mining District), Placer Co., California, USAi
Regional Level Types
Ophir Mining District (Auburn Mining District; Duncan Hill Mining District)Mining District
Placer Co.County
CaliforniaState
USACountry

This page is currently not sponsored. Click here to sponsor this page.
Key
Latitude & Longitude (WGS84):
38° 53' 26'' North , 121° 7' 22'' West
Latitude & Longitude (decimal):
Locality type:


Location: A Au-Ag-Pb-Cu mining area located in sec. 18, T12N, R8E, MDM. The center of this district is about two miles west of the old town area of Auburn. Discovered in 1851. The district is oblong shaped and covers several square miles. It trends west-northwest and is about 5 miles long by 2 miles wide. Access is via paved rural roads.

This lode-gold district is located in southwestern Placer County, in the vicinity of the old town of Ophir and includes many individual mines developed along a west-northwest-trending belt of quartz veins, which formed at the contact between granitic and metavolcanic rocks a few miles west of the town of Auburn. It is the most productive lode-gold district in Placer County. It extends east to Auburn and west to Gold Hill and also includes what was known as the Duncan Hill Mining District, which was centered about half way between the towns of Ophir and Auburn. It adjoins the Penryn District on the NE.

The district is situated among hills that are subdivided by semi-rural residential development. Vegetation consists of a mixture of grass and oak woodland. The topography of the area underlain by the metavolcanic rock is rugged in places, while that underlain by the quartz diorite is more subdued.

History: Gold-bearing surface gravels were discovered at Ophir and Auburn in 1848 and for several years yielded substantial amounts of the mineral. The quartz veins were then developed, and the Ophir and Duncan Hill districts were organized. Appreciable amounts of high-grade gold ore were recovered during the 1860's, 1870's, and 1880's, but mining activity in the district declined after that. The mines were active again from the early 1900's through the 1930's with substantial production, but little has been done since. The value of the total output of the district is estimated at more than $5 million (period values).

Gold-bearing surface gravels were discovered at Ophir and Auburn in 1848 and for several years yielded substantial amounts of the mineral. The quartz veins were then developed, and the Ophir and Duncan Hill districts were organized. Appreciable amounts of high-grade gold ore were recovered during the 1860's, 1870's, and 1880's, but mining activity in the district declined after that. The mines were active again from the early 1900's through the 1930's with substantial production, but little has been done since. The value of total output of the district is estimated at more than $5 million (period values).

Processing of ores from this district in the early days was hindered by the presence of abundant sulfides. A chief period of production was in the 1870's. From the mid-1930's to 1942, the district was also very productive, but between 1942 to 1959, less than 100 ounces per year were produced (Koschmann and Bergendahl, 1968). Mining activity subsequent to that time is not known, but is assumed to have been very minor.

There are at least 50 known lode mines in the Ophir District. The most productive mines were the Bellevue, Crater Hill, Gold Blossom, Hathaway, Oro Fino (Oro Fina), and Three Star. The Crater Hill may have been the largest producer in the district (estimated by Clark to be $750,000 [period values]). The Oro Fina was the last-worked important producer in the district as of the 1930's.

Amalgamation and flotation processes were used at mines in this district. Concentrates (sulfide minerals) were typically shipped elsewhere for processing.

Geology: The mineralized zone is on the NE flank of a granodiorite and quartz-diorite stock that is intrusive into amphibolite schist. A series of west-northwest-striking and south-dipping quartz veins occur in the granitic rocks or along the granitic rock-amphibolite schist contact. A few veins are in the amphibolite. The ore contains free gold in places with
often abundant pyrite, galena, and chalcopyrite; much of the ore is base. Milling ore ranged from ½ to 1 ounce of gold per ton. Considerable high-grade ore was taken close to the surface during the early day's. The veins range from one to five feet in thickness, and several were mined to depths of more than 1,000 feet. The ore shoots had stoping lengths of up to 250 feet.

The Ophir District is situated at the western edge of the Sierra Nevada metamorphic belt. Here, metamorphosed Jurassic island-arc volcanic rocks have been intruded by quartz diorite of the Lower Cretaceous Penryn Pluton (Olmsted, 1971; Wagner and others, 1981). The mines of the district are developed in a system of quartz veins along and adjacent to the contact between the plutonic rock and metavolcanic rock. Both types of rock serve as hosts for the quartz veins. Younger igneous dikes of dioritic composition intrude the plutonic and metavolcanic rocks and are also associated with the quartz veins in places.

In general, the vein system of the district strikes west-northwest, and dips of individual veins are about 40-80SW. There is a lesser set of veins within the central part of the system, which strike northeast and dip 20-60SE. Lindgren (1892) reported that the westerly striking set of veins was more important economically. Thicknesses of veins in the district range from a few inches up to 10 or 20 feet; the average is about one foot. Several veins are traceable for 1.5 miles or more. The veins are present in both the quartz diorite and metavolcanic rocks, and commonly cross the contact. In the quartz diorite, the hanging walls of the quartz veins typically are composed of the diorite dikes mentioned above, although some ore bodies are not associated with dikes. The dikes are seldom over 1-2 feet thick and in some places are altered to amphibolite (Lindgren, 1892).

The veins are typically characterized by ribbon structure and contain vugs and cavities locally, which are strong evidence for origination of the veins by filling of open fissures rather than by replacement of wallrock. Undulatory extinction and comminution of quartz in the veins suggest movements along some of the veins. Gangue consists almost entirely of quartz with very minor calcite and chalcedony.

Lindgren (1892) reported that the wallrocks of quartz diorite and amphibolite are intensely altered; the zones of alteration are a few inches to a few feet wide and are composed of grayish to white fine-grained rock where formerly metavolcanic rock and grayish green rock where formerly quartz diorite. Alteration minerals in the quartz diorite and metavolcanic wall rock consist of aggregates of carbonate (mostly calcite), sericite, and euhedral pyrite. Pyrite is more abundant in the altered rock than in the veins and unaltered rock. Lindgren (1892) interpreted the alteration to be similar in both types of wallrock and was the result of carbonatization. In some places, the altered rock contains small amounts of gold and silver even though no quartz veins are present. In other places, small veinlets of quartz traverse the rock.

Lindgren (1892) observed that the character of the ores in the two main types of host rock are somewhat different. Those in the quartz diorite are low grade, rich in silver, and very extensive. Those in the metavolcanic rock are richer, contain less silver, and are of small extent (commonly present as ?pockets?).

Concentration of sulfides was generally considered an indicator of richness of the gold-quartz ore; galena is an especially good indicator. Milling ore contained 1.5 to 3% sulfides. Pyrite is the most common sulfide.

Of note near the northwest edge of the district are the orientations of a third set of veins, which were developed at the Three Star Mine and a few other mines. This vein system trends north-northeast rather than west-northwest.

Geologic structures: Regional structure include the Bear Mountains Fault Zone.

Mineralogy: Mineralization is Cretaceous lode Au veins in amphibolite and granitic rocks. Ore bodies are generally tabular. Mineral occurrence model information: Model code: 273; USGS model code: 36a; Deposit model name: Low-sulfide Au-quartz vein; Mark3 model number: 27. Host rocks include the Early Cretaceous (Chronological age: 139) quartz diorite of the Penryn pluton; the Late Jurassic amphibolite of the Copper Hill Volcanics; and Cretaceous diorite dikes. Controls for ore emplacement included quartz veins filling fractures developed in quartz diorite and metamorphosed mafic to intermediate volcanic rock. Lindgren (1892) observed that where the quartz veins intersected zones of metavolcanic rock enriched in pyrite and copper sulfides (termed "iron belts"), the veins were more enriched in gold. Also, some localities where veins intersected were the sites of pockets or rich ore shoots. Local alteration includes carbonatization, calcite, sericite, pyrite, minor chlorite formed as selvages a few inches to a few feet wide in wallrock immediately adjacent to quartz veins. Local rocks include Mesozoic granitic rocks, unit 3 (Sierra Nevada, Death Valley area, Northern Mojave Desert and Transverse Ranges)

The ore bodies of the Ophir District are developed in gold-bearing quartz veins emplaced in quartz diorite of the Lower Cretaceous Penryn Pluton and in older Jurassic metavolcanic rocks, which are mafic to intermediate composition. In places, dioritic dikes are associated with the quartz veins. The veins are present in three sets. The dominant set trends west-northwest, has dips mainly to the southwest, and was the most important source of gold in the district. A second set, which intersects the central part of the dominant set, trends northeast, with dips to the southeast. The third set is minor and trends northerly along the west edge of the district.

The quartz veins are typically characterized by ribbon structure and contain vugs and cavities locally, which are strong evidence for origination of the veins by filling of open fissures rather than by replacement of wallrock. Undulatory extinction and comminution of quartz in the veins suggest movements along some of the veins. Gangue consists almost entirely of quartz with very minor calcite and chalcedony. Ore was typically found in shoots that extended down-dip within the quartz veins. Where the veins intersect zones of metavolcanic rock enriched in pyrite and copper sulfides (termed ?iron belts?), miners observed that the veins were more enriched in gold.

Ore consists mainly of native gold (electrum) and sulfides that are auriferous and argentiferous. The ore bodies are noteworthy for their high silver content. Concentration of sulfides was generally considered an indicator of richness of the gold-quartz ore; galena is an especially good indicator. Milling ore typically contained 1.5 to 3% sulfides, with pyrite the most common sulfide. Narrow zones of altered wallrock adjacent to the quartz veins also contain sulfides, some of which carry minor amounts of gold and silver.

An extensive summary of the lode-gold deposits of the Ophir District was presented by Lindgren (1892).

Commodity Information: The district is notable for the large proportion of silver in the ore - most native gold mined was in the form of electrum. Gold seldom exceeded .700 in fineness and was as low as .500 to .600; the average fineness in California was about .850 (Lindgren, 1892). Regarding sulfides, Lindgren (1892) reported that gold was typically found in the pyrite, while silver was found in the tetrahedrite, galena, and sphalerite. Some specimen gold was produced in this district. Ore Materials: Native gold (mainly as electrum), auriferous and argentiferous sulfides (pyrite, chalcopyrite, galena, sphalerite, arsenopyrite, tetrahedite, molybdenite), native silver, stibnite, tellurides, selenides. Gangue Materials: Quartz, calcite, chalcedony.

Workings Information: This district contains numerous small underground mines, which were developed along the extensive system of quartz veins that cut the Penryn Pluton and Jurassic metavolcanic rocks. Workings typically consisted of shafts, adits, drifts, and crosscuts with associated stoping of the ore shoots. The Crater Hill Mine may have the deepest workings in the district; the shaft was at least 800 feet deep in the early 1890's. Logan (1936) reported, however, that the shaft of the Oro Fina Mine reached a depth of 860 feet on a 72-degree incline during the 1930's. Workings of most mines were probably limited to less than 500 feet deep.

Waring (1915) provided a figure that shows the claims of the district as of the early 20th century.

Production Information: Clark (1970) estimated production in this district to be in excess of $5 million (period values), which may include both lode and placer sources. Koschmann and Bergendahl (1968) estimated lode production to be about 255,500 ounces of Au.

Mines: Belmont, Black Ledge, Centenial ($150,000+), Conrad ($50,000), Crater ($750,000), Doig, Eclipse ($100,000+), Gold Blossom ($216,000+), Grass Ravine, Green ($150,000+), Green Emigrant ($150,000+), Hathaway ($336,000), Julian, Mina Rica ($55,000), Moore ($180,000), Oro Fino ($500,000+), Pine Tree, Rock Creek ($200,000 ?), St. Lawrence, St. Patrick ($148,000+), Three Stars ($415,000).

Regions containing this locality

Pacific OceanOcean
North America PlateTectonic Plate

Select Mineral List Type

Standard Detailed Strunz Dana 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

23 valid minerals.

Detailed Mineral List:

Acanthite
Formula: Ag2S
Reference: Logan, Clarence August (1936), Gold mines of Placer County: California Journal of Mines and Geology, California Division Mines (Report 32): 32(1): 11, 22; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 108.
Arsenopyrite
Formula: FeAsS
Reference: Lindgren, Waldemar (1894a), The gold-silver veins of Ophir, California: USGS 14th. Annual Report, part 2: 273; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 87.
Calcite
Formula: CaCO3
Reference: USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10310713.
Chalcopyrite
Formula: CuFeS2
Localities: Reported from at least 10 localities in this region.
'Chlorite Group'
Reference: USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10310713.
Chromite
Formula: Fe2+Cr3+2O4
Description: Occurs as nodular masses coated by pennine, kämmererite and good crystals of uvarovite.
Reference: Melhase, John (1935c), Some garnet localities of California: Mineralogist: 3(11): 23; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 141.
Clinochlore
Formula: Mg5Al(AlSi3O10)(OH)8
Reference: Melhase, John (1935c), Some garnet localities of California: Mineralogist: 3(11): 23; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 141.
Clinochlore var: Chromian Clinochlore
Formula: Mg5(Al,Cr)2Si3O10(OH)8
Reference: Melhase, John (1935c), Some garnet localities of California: Mineralogist: 3(11): 23; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 141.
Clinochlore var: Pennine
Formula: Mg5Al(AlSi3O10)(OH)8
Reference: Melhase, John (1935c), Some garnet localities of California: Mineralogist: 3(11): 23; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 141.
Copper
Formula: Cu
Reference: Lindgren, Waldemar (1894a), The gold-silver veins of Ophir, California: UGS 14th. Annual Report, part 2: 272; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 158; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 49.
'Electrum'
Formula: (Au, Ag)
Galena
Formula: PbS
Localities: Reported from at least 18 localities in this region.
Gold
Formula: Au
Localities: Reported from at least 79 localities in this region.
Hausmannite
Formula: Mn2+Mn3+2O4
Reference: Fairbanks, Harold W. (1890), Geology of the Mother Lode region: California Mining Bureau. Report 10: 47; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 215.
Kalinite
Formula: KAl(SO4)2 · 11H2O
Description: Occurs in slates.
Reference: Hanks, Henry Garber (1884), Fourth report of the State Mineralogist: California Mining Bureau. Report 4, 410 pp.: 68; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 293.
Malachite
Formula: Cu2(CO3)(OH)2
Marcasite
Formula: FeS2
Reference: U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
'Mariposite'
Formula: K(Al,Cr)2(Al,Si)4O10(OH)2
Reference: Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 256.
Molybdenite
Formula: MoS2
Muscovite
Formula: KAl2(AlSi3O10)(OH)2
Muscovite var: Phengite
Formula: KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
Reference: Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 256.
Muscovite var: Sericite
Formula: KAl2(AlSi3O10)(OH)2
Reference: USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10310713.
Pyrargyrite
Formula: Ag3SbS3
Description: Occurs in gold-quartz.
Reference: Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 140.
Pyrite
Formula: FeS2
Localities: Reported from at least 23 localities in this region.
Quartz
Formula: SiO2
Localities: Reported from at least 68 localities in this region.
Quartz var: Chalcedony
Formula: SiO2
Silver
Formula: Ag
Sphalerite
Formula: ZnS
Localities: Reported from at least 6 localities in this region.
Stibnite
Formula: Sb2S3
Tetrahedrite
Formula: Cu6Cu4(Fe2+,Zn)2Sb4S12S
Localities: Reported from at least 6 localities in this region.
Uvarovite
Formula: Ca3Cr2(SiO4)3
Description: Occurs as good crystals.
Reference: Melhase, John (1935c), Some garnet localities of California: Mineralogist: 3(11): 23; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 141.

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
Copper1.AA.05Cu
'Electrum'1.AA.05(Au, Ag)
Gold1.AA.05Au
Silver1.AA.05Ag
Group 2 - Sulphides and Sulfosalts
Acanthite2.BA.35Ag2S
Arsenopyrite2.EB.20FeAsS
Chalcopyrite2.CB.10aCuFeS2
Galena2.CD.10PbS
Marcasite2.EB.10aFeS2
Molybdenite2.EA.30MoS2
Pyrargyrite2.GA.05Ag3SbS3
Pyrite2.EB.05aFeS2
Sphalerite2.CB.05aZnS
Stibnite2.DB.05Sb2S3
Tetrahedrite2.GB.05Cu6Cu4(Fe2+,Zn)2Sb4S12S
Group 4 - Oxides and Hydroxides
Chromite4.BB.05Fe2+Cr3+2O4
Hausmannite4.BB.10Mn2+Mn3+2O4
Quartz4.DA.05SiO2
var: Chalcedony4.DA.05SiO2
Group 5 - Nitrates and Carbonates
Calcite5.AB.05CaCO3
Malachite5.BA.10Cu2(CO3)(OH)2
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
Kalinite7.CC.15KAl(SO4)2 · 11H2O
Group 9 - Silicates
Clinochlore9.EC.55Mg5Al(AlSi3O10)(OH)8
var: Chromian Clinochlore9.EC.55Mg5(Al,Cr)2Si3O10(OH)8
var: Pennine9.EC.55Mg5Al(AlSi3O10)(OH)8
Muscovite9.EC.15KAl2(AlSi3O10)(OH)2
var: Phengite9.EC.15KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
var: Sericite9.EC.15KAl2(AlSi3O10)(OH)2
Uvarovite9.AD.25Ca3Cr2(SiO4)3
Unclassified Minerals, Rocks, etc.
'Chlorite Group'-
'Mariposite'-K(Al,Cr)2(Al,Si)4O10(OH)2

List of minerals arranged by Dana 8th Edition classification

Group 1 - NATIVE ELEMENTS AND ALLOYS
Metals, other than the Platinum Group
Copper1.1.1.3Cu
Gold1.1.1.1Au
Silver1.1.1.2Ag
Group 2 - SULFIDES
AmBnXp, with (m+n):p = 2:1
Acanthite2.4.1.1Ag2S
AmXp, with m:p = 1:1
Galena2.8.1.1PbS
Sphalerite2.8.2.1ZnS
AmBnXp, with (m+n):p = 1:1
Chalcopyrite2.9.1.1CuFeS2
AmBnXp, with (m+n):p = 2:3
Stibnite2.11.2.1Sb2S3
AmBnXp, with (m+n):p = 1:2
Arsenopyrite2.12.4.1FeAsS
Marcasite2.12.2.1FeS2
Molybdenite2.12.10.1MoS2
Pyrite2.12.1.1FeS2
Group 3 - SULFOSALTS
3 <ø < 4
Tetrahedrite3.3.6.1Cu6Cu4(Fe2+,Zn)2Sb4S12S
ø = 3
Pyrargyrite3.4.1.2Ag3SbS3
Group 7 - MULTIPLE OXIDES
AB2X4
Chromite7.2.3.3Fe2+Cr3+2O4
Hausmannite7.2.7.1Mn2+Mn3+2O4
Group 14 - ANHYDROUS NORMAL CARBONATES
A(XO3)
Calcite14.1.1.1CaCO3
Group 16a - ANHYDROUS CARBONATES CONTAINING HYDROXYL OR HALOGEN
Malachite16a.3.1.1Cu2(CO3)(OH)2
Group 29 - HYDRATED ACID AND NORMAL SULFATES
AB(XO4)2·xH2O
Kalinite29.5.4.2KAl(SO4)2 · 11H2O
Group 51 - NESOSILICATES Insular SiO4 Groups Only
Insular SiO4 Groups Only with cations in [6] and >[6] coordination
Uvarovite51.4.3b.3Ca3Cr2(SiO4)3
Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings
Sheets of 6-membered rings with 2:1 layers
Muscovite71.2.2a.1KAl2(AlSi3O10)(OH)2
Sheets of 6-membered rings interlayered 1:1, 2:1, and octahedra
Clinochlore71.4.1.4Mg5Al(AlSi3O10)(OH)8
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Unclassified Minerals, Mixtures, etc.
'Chlorite Group'-
Clinochlore
var: Chromian Clinochlore
-Mg5(Al,Cr)2Si3O10(OH)8
var: Pennine-Mg5Al(AlSi3O10)(OH)8
'Electrum'-(Au, Ag)
'Mariposite'-K(Al,Cr)2(Al,Si)4O10(OH)2
Muscovite
var: Phengite
-KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
var: Sericite-KAl2(AlSi3O10)(OH)2
Quartz
var: Chalcedony
-SiO2

List of minerals for each chemical element

HHydrogen
H MalachiteCu2(CO3)(OH)2
H MaripositeK(Al,Cr)2(Al,Si)4O10(OH)2
H Clinochlore (var: Pennine)Mg5Al(AlSi3O10)(OH)8
H Clinochlore (var: Chromian Clinochlore)Mg5(Al,Cr)2Si3O10(OH)8
H KaliniteKAl(SO4)2 · 11H2O
H Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
H MuscoviteKAl2(AlSi3O10)(OH)2
H ClinochloreMg5Al(AlSi3O10)(OH)8
H Muscovite (var: Phengite)KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
CCarbon
C MalachiteCu2(CO3)(OH)2
C CalciteCaCO3
OOxygen
O QuartzSiO2
O MalachiteCu2(CO3)(OH)2
O MaripositeK(Al,Cr)2(Al,Si)4O10(OH)2
O ChromiteFe2+Cr23+O4
O Clinochlore (var: Pennine)Mg5Al(AlSi3O10)(OH)8
O UvaroviteCa3Cr2(SiO4)3
O Clinochlore (var: Chromian Clinochlore)Mg5(Al,Cr)2Si3O10(OH)8
O HausmanniteMn2+Mn23+O4
O KaliniteKAl(SO4)2 · 11H2O
O Quartz (var: Chalcedony)SiO2
O CalciteCaCO3
O Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
O MuscoviteKAl2(AlSi3O10)(OH)2
O ClinochloreMg5Al(AlSi3O10)(OH)8
O Muscovite (var: Phengite)KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
MgMagnesium
Mg Clinochlore (var: Pennine)Mg5Al(AlSi3O10)(OH)8
Mg Clinochlore (var: Chromian Clinochlore)Mg5(Al,Cr)2Si3O10(OH)8
Mg ClinochloreMg5Al(AlSi3O10)(OH)8
Mg Muscovite (var: Phengite)KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
AlAluminium
Al MaripositeK(Al,Cr)2(Al,Si)4O10(OH)2
Al Clinochlore (var: Pennine)Mg5Al(AlSi3O10)(OH)8
Al Clinochlore (var: Chromian Clinochlore)Mg5(Al,Cr)2Si3O10(OH)8
Al KaliniteKAl(SO4)2 · 11H2O
Al Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
Al MuscoviteKAl2(AlSi3O10)(OH)2
Al ClinochloreMg5Al(AlSi3O10)(OH)8
Al Muscovite (var: Phengite)KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
SiSilicon
Si QuartzSiO2
Si MaripositeK(Al,Cr)2(Al,Si)4O10(OH)2
Si Clinochlore (var: Pennine)Mg5Al(AlSi3O10)(OH)8
Si UvaroviteCa3Cr2(SiO4)3
Si Clinochlore (var: Chromian Clinochlore)Mg5(Al,Cr)2Si3O10(OH)8
Si Quartz (var: Chalcedony)SiO2
Si Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
Si MuscoviteKAl2(AlSi3O10)(OH)2
Si ClinochloreMg5Al(AlSi3O10)(OH)8
Si Muscovite (var: Phengite)KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
SSulfur
S SphaleriteZnS
S GalenaPbS
S PyriteFeS2
S ChalcopyriteCuFeS2
S AcanthiteAg2S
S TetrahedriteCu6Cu4(Fe2+,Zn)2Sb4S12S
S MolybdeniteMoS2
S MarcasiteFeS2
S StibniteSb2S3
S ArsenopyriteFeAsS
S KaliniteKAl(SO4)2 · 11H2O
S PyrargyriteAg3SbS3
KPotassium
K MaripositeK(Al,Cr)2(Al,Si)4O10(OH)2
K KaliniteKAl(SO4)2 · 11H2O
K Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
K MuscoviteKAl2(AlSi3O10)(OH)2
K Muscovite (var: Phengite)KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
CaCalcium
Ca UvaroviteCa3Cr2(SiO4)3
Ca CalciteCaCO3
CrChromium
Cr MaripositeK(Al,Cr)2(Al,Si)4O10(OH)2
Cr ChromiteFe2+Cr23+O4
Cr UvaroviteCa3Cr2(SiO4)3
Cr Clinochlore (var: Chromian Clinochlore)Mg5(Al,Cr)2Si3O10(OH)8
MnManganese
Mn HausmanniteMn2+Mn23+O4
FeIron
Fe PyriteFeS2
Fe ChalcopyriteCuFeS2
Fe TetrahedriteCu6Cu4(Fe2+,Zn)2Sb4S12S
Fe MarcasiteFeS2
Fe ChromiteFe2+Cr23+O4
Fe ArsenopyriteFeAsS
Fe Muscovite (var: Phengite)KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
CuCopper
Cu ChalcopyriteCuFeS2
Cu MalachiteCu2(CO3)(OH)2
Cu TetrahedriteCu6Cu4(Fe2+,Zn)2Sb4S12S
Cu CopperCu
ZnZinc
Zn SphaleriteZnS
Zn TetrahedriteCu6Cu4(Fe2+,Zn)2Sb4S12S
AsArsenic
As ArsenopyriteFeAsS
MoMolybdenum
Mo MolybdeniteMoS2
AgSilver
Ag Electrum(Au, Ag)
Ag SilverAg
Ag AcanthiteAg2S
Ag PyrargyriteAg3SbS3
SbAntimony
Sb TetrahedriteCu6Cu4(Fe2+,Zn)2Sb4S12S
Sb StibniteSb2S3
Sb PyrargyriteAg3SbS3
AuGold
Au Electrum(Au, Ag)
Au GoldAu
PbLead
Pb GalenaPbS

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Irelan, William, Jr. (1888b), Eighth annual report of the State: California Mining Bureau. (Report 8), 946 pp.: 460-462.
Hobson, John B. (1890), Ophir mining district, California Mining Bureau (Report 10): 10: 427-433.
Lindgren, Waldemar (1892), Gold-silver veins at Ophir: USGS 14th Annual Report, part 2: 249-284.
Lindgren, Waldemar (1894a), The gold-silver veins of Ophir, California: UGS 14th. Ann. Report, part 2: 243-284; […(abstract): Mining and Scientific Press: 71: 216, 233 (1895); Journal of Geology: 4: 373-374 (1896); …Nature: 53: 466 (1896)]: 273.
Lindgren, Waldemar (1894b), Description of the gold belt; description of the Sacramento sheet. USGS Geologic Atlas, Sacramento folio (Folio No. 5), 3 pp.
Waring, Clarence A. (1919), Butte, Placer, Sacramento, Yuba Counties: California Bureau of Mines (Report 15): 15: 319.
Logan, Clarence August (1936), Gold Mines of Placer County: California Journal of Mines and Geology, California Division Mines (Report 32): 32(1): 28-31.
Lydon, P. A. (1959), Geology along U. S. Highway 40: Mineral Information Service: 12(8): 1-9.
Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 87, 269, 545.
Koschman, A.H. and Bergendahl, M.H. (1968) Principal gold-producing districts of the United Sattes. USGS Professional Paper 610, 283 pp.
Clark, Wm. B. (1970a) Gold districts of California: California Division Mines & Geology Bulletin 193: 102-103.
Olmsted, F.H. (1971), Pre-Cenozoic geology of the south half of the Auburn 15-minute quadrangle, California: U.S. Geological Survey Bulletin 1341, 30 p.
Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 29 (map 2-17), 80, 134.
USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10310713.
USGS 7.5-minute Auburn, California, quadrangle topo map.

USGS MRDS Record:10310713

Localities in this Region


This page 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.
 
Mineral and/or Locality  
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization. Public Relations by Blytheweigh.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2020, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: February 16, 2020 20:00:25 Page generated: June 26, 2019 21:10:49
Go to top of page