Vote for your favorite mineral in #MinCup26! - Bournonite vs. Vesuvianite
Cogwheels of bournonite are up against colourful vesuvianite.
Log InRegister
Quick Links : The Mindat ManualThe Rock H. Currier Digital LibraryMindat Newsletter [Free Download]
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 ElementsThe Rock H. Currier Digital LibraryGeologic TimeExplore Fossils
Minerals by PropertiesMinerals by ChemistryMineral Visual ExplorerAdvanced 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 MuseumsClubs & OrganizationsMineral Shows & EventsThe Mindat DirectoryDevice SettingsThe Mineral QuizTime Machine
Photo SearchPhoto GalleriesSearch by ColorPhoto Colour ExplorerNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day GalleryPhotography

Hornitos Mining District, West Belt, Mariposa County, California, USAi
Regional Level Types
Hornitos Mining DistrictMining District
West Belt- not defined -
Mariposa CountyCounty
CaliforniaState
USACountry

This page is currently not sponsored. Click here to sponsor this page.
PhotosMapsSearchMineralogy
Latitude & Longitude (WGS84):
37° North , 120° West (est.)
Estimate based on other nearby localities or region boundaries.
Margin of Error:
~26km
Mindat Locality ID:
249228
Long-form identifier:
mindat:1:2:249228:8
GUID (UUID V4):
0


Location: The Hornitos district is in the Sierra Nevada west gold belt in western Mariposa County about 15 miles west of the town of Mariposa (see fig. 4, Bulletin 193). The district contains a several-mile wide belt of lode-gold mines that extends from the vicinity of the Exchequer Reservoir SSE through Hornitos to the Indian Gulch area.

History: The streams in the area were first worked in 1849, and lode mining began in 1850 at the Washington Mine. The town was first settled by Mexicans who had been driven out of nearby Quartzburg. The name Hornitos is a diminutive of "homo" or small bake oven, from the Spanish. Mining activity was great from the 1860's through the 1880's, lesser from the 1890's to the 1920's. The Mt. Gaines Mine was worked on a major scale during the 1930s. Since World War II the area has been prospected, but there has been very little recorded production. Historically, this is the most productive district of the Sierra Nevada West gold belt.

Geology: The district is underlain by greenstone and green schist in the West portion and slate in the East. Also present are smaller amounts of amphibolite, mica schist, and hornfels. A number of small granodiorite intrusions are exposed, along the margins of which chiastolite-mica schist has developed.

Ore Deposits: A number of north-trending quartz veins and stringers containing free gold and varying amounts of sulfides, chiefly pyrite, are present, as well as several large bodies of mineralized greenstone or "gray ore." Some of the veins have very flat dips. The ore shoots vary considerably in size with stoping lengths ranging from a few to as much as 400 feet. Some of the veins have been mined to inclined depths of more than 1500 feet. Milling-grade ore commonly contains from 1/3, to more than ½ ounce per ton in gold.

Mines: Badger ($80,000+), Doss ($100,000), Duncan, Lost Douglas, Martinez, Mt. Gaines ($3.59 million). Number 1 Mine, Number 5 Mine, Number 8 Mine, Number 9 Mine, Ruth Pierce ($600,000), and the Washington Mine ($2,377,000).

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

33 valid minerals.

Rock Types Recorded


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

Select Rock List Type

Alphabetical List Tree Diagram

Detailed Mineral List:

Acanthite
Formula: Ag2S
Alunite
Formula: KAl3(SO4)2(OH)6
Description: Occurs as a constituent of quartzite.
Andalusite
Formula: Al2(SiO4)O
Ankerite
Formula: Ca(Fe2+,Mg)(CO3)2
Arsenopyrite
Formula: FeAsS
Baryte
Formula: BaSO4
Bornite
Formula: Cu5FeS4
Calcite
Formula: CaCO3
Chalcocite
Formula: Cu2S
Chalcopyrite
Formula: CuFeS2
Localities: Reported from at least 7 localities in this region.
'Chlorite Group'
Cooperite
Formula: PtS
Covellite
Formula: CuS
Galena
Formula: PbS
Localities:
Hematite
Formula: Fe2O3
Isoferroplatinum
Formula: Pt3Fe
'Limonite'
Malachite
Formula: Cu2(CO3)(OH)2
Muscovite
Formula: KAl2(AlSi3O10)(OH)2
Muscovite var. Sericite
Formula: KAl2(AlSi3O10)(OH)2
Native Gold
Formula: Au
Localities: Reported from at least 31 localities in this region.
Native Iridium
Formula: (Ir,Os,Ru)
Native Osmium
Formula: (Os,Ir,Ru)
Native Platinum
Formula: Pt
Native Ruthenium
Formula: (Ru,Ir)
Native Silver ?
Formula: Ag
Description: (Probably refers to the silver content in the native gold, not to the presence of the discrete species "native silver".)
Native Sulphur
Formula: S8
Description: Loose microcrystals filling cast left by decomposed pyrite crystal in a gold-bearing quartz vein.
Proustite
Formula: Ag3AsS3
'Psilomelane'
Pyrargyrite
Formula: Ag3SbS3
Pyrite
Formula: FeS2
Localities: Reported from at least 14 localities in this region.
Description: Abundant.
Pyrophyllite
Formula: Al2Si4O10(OH)2
Colour: Golden-yellow
Description: Radiating tufts.
Quartz
Formula: SiO2
Localities: Reported from at least 22 localities in this region.
Quartz var. Milky Quartz
Formula: SiO2
Rhodonite
Formula: CaMn3Mn[Si5O15]
'Serpentine Subgroup'
Formula: D3[Si2O5](OH)4
Sphalerite
Formula: ZnS
Description: Occurs as a substantial deposit.
Tetraferroplatinum
Formula: PtFe
'Tetrahedrite Subgroup'
Formula: Cu6(Cu4C2+2)Sb4S12S
Todorokite
Formula: (Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
References:
Petrov, Alfredo (n.d.) Personal Communication.PXRD by John Attard, XRF by Alfredo Petrov May 2014

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
Native Gold1.AA.05Au
Native Silver ?1.AA.05Ag
Native Osmium1.AF.05(Os,Ir,Ru)
Native Ruthenium1.AF.05(Ru,Ir)
Native Iridium1.AF.10(Ir,Os,Ru)
Native Platinum1.AF.10Pt
Isoferroplatinum1.AG.35Pt3Fe
Tetraferroplatinum1.AG.40PtFe
Native Sulphur1.CC.05S8
Group 2 - Sulphides and Sulfosalts
Chalcocite2.BA.05Cu2S
Bornite2.BA.15Cu5FeS4
Acanthite2.BA.35Ag2S
Covellite2.CA.05aCuS
Sphalerite2.CB.05aZnS
Chalcopyrite2.CB.10aCuFeS2
Cooperite2.CC.35bPtS
Galena2.CD.10PbS
Pyrite2.EB.05aFeS2
Arsenopyrite2.EB.20FeAsS
Proustite2.GA.05Ag3AsS3
Pyrargyrite2.GA.05Ag3SbS3
'Tetrahedrite Subgroup'2.GB.05Cu6(Cu4C2+2)Sb4S12S
Group 4 - Oxides and Hydroxides
Hematite4.CB.05Fe2O3
Quartz4.DA.05SiO2
var. Milky Quartz4.DA.05SiO2
Todorokite4.DK.10(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
Group 5 - Nitrates and Carbonates
Calcite5.AB.05CaCO3
Ankerite5.AB.10Ca(Fe2+,Mg)(CO3)2
Malachite5.BA.10Cu2(CO3)(OH)2
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
Baryte7.AD.35BaSO4
Alunite7.BC.10KAl3(SO4)2(OH)6
Group 9 - Silicates
Andalusite9.AF.10Al2(SiO4)O
Rhodonite9.DK.05CaMn3Mn[Si5O15]
Pyrophyllite9.EC.10Al2Si4O10(OH)2
Muscovite9.EC.15KAl2(AlSi3O10)(OH)2
var. Sericite9.EC.15KAl2(AlSi3O10)(OH)2
Unclassified
'Chlorite Group'-
'Limonite'-
'Psilomelane'-
'Serpentine Subgroup'-D3[Si2O5](OH)4

List of minerals for each chemical element

HHydrogen
H AluniteKAl3(SO4)2(OH)6
H MalachiteCu2(CO3)(OH)2
H MuscoviteKAl2(AlSi3O10)(OH)2
H PyrophylliteAl2Si4O10(OH)2
H Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
H Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
H Serpentine SubgroupD3[Si2O5](OH)4
CCarbon
C AnkeriteCa(Fe2+,Mg)(CO3)2
C CalciteCaCO3
C MalachiteCu2(CO3)(OH)2
OOxygen
O AluniteKAl3(SO4)2(OH)6
O AndalusiteAl2(SiO4)O
O AnkeriteCa(Fe2+,Mg)(CO3)2
O BaryteBaSO4
O CalciteCaCO3
O HematiteFe2O3
O MalachiteCu2(CO3)(OH)2
O MuscoviteKAl2(AlSi3O10)(OH)2
O PyrophylliteAl2Si4O10(OH)2
O QuartzSiO2
O RhodoniteCaMn3Mn[Si5O15]
O Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
O Quartz var. Milky QuartzSiO2
O Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
O Serpentine SubgroupD3[Si2O5](OH)4
NaSodium
Na Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
MgMagnesium
Mg AnkeriteCa(Fe2+,Mg)(CO3)2
Mg Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
AlAluminium
Al AluniteKAl3(SO4)2(OH)6
Al AndalusiteAl2(SiO4)O
Al MuscoviteKAl2(AlSi3O10)(OH)2
Al PyrophylliteAl2Si4O10(OH)2
Al Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
Al Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
SiSilicon
Si AndalusiteAl2(SiO4)O
Si MuscoviteKAl2(AlSi3O10)(OH)2
Si PyrophylliteAl2Si4O10(OH)2
Si QuartzSiO2
Si RhodoniteCaMn3Mn[Si5O15]
Si Quartz var. Milky QuartzSiO2
Si Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
Si Serpentine SubgroupD3[Si2O5](OH)4
SSulfur
S AcanthiteAg2S
S AluniteKAl3(SO4)2(OH)6
S ArsenopyriteFeAsS
S BaryteBaSO4
S BorniteCu5FeS4
S ChalcopyriteCuFeS2
S ChalcociteCu2S
S CooperitePtS
S CovelliteCuS
S GalenaPbS
S ProustiteAg3AsS3
S PyrargyriteAg3SbS3
S PyriteFeS2
S SphaleriteZnS
S Native SulphurS8
S Tetrahedrite SubgroupCu6(Cu4C22+)Sb4S12S
KPotassium
K AluniteKAl3(SO4)2(OH)6
K MuscoviteKAl2(AlSi3O10)(OH)2
K Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
K Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
CaCalcium
Ca AnkeriteCa(Fe2+,Mg)(CO3)2
Ca CalciteCaCO3
Ca RhodoniteCaMn3Mn[Si5O15]
Ca Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
MnManganese
Mn RhodoniteCaMn3Mn[Si5O15]
Mn Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
FeIron
Fe AnkeriteCa(Fe2+,Mg)(CO3)2
Fe ArsenopyriteFeAsS
Fe BorniteCu5FeS4
Fe ChalcopyriteCuFeS2
Fe HematiteFe2O3
Fe IsoferroplatinumPt3Fe
Fe PyriteFeS2
Fe TetraferroplatinumPtFe
CuCopper
Cu BorniteCu5FeS4
Cu ChalcopyriteCuFeS2
Cu ChalcociteCu2S
Cu CovelliteCuS
Cu MalachiteCu2(CO3)(OH)2
Cu Tetrahedrite SubgroupCu6(Cu4C22+)Sb4S12S
ZnZinc
Zn SphaleriteZnS
AsArsenic
As ArsenopyriteFeAsS
As ProustiteAg3AsS3
SrStrontium
Sr Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
RuRuthenium
Ru Native Iridium(Ir,Os,Ru)
Ru Native Osmium(Os,Ir,Ru)
Ru Native Ruthenium(Ru,Ir)
AgSilver
Ag AcanthiteAg2S
Ag ProustiteAg3AsS3
Ag PyrargyriteAg3SbS3
Ag Native SilverAg
SbAntimony
Sb PyrargyriteAg3SbS3
Sb Tetrahedrite SubgroupCu6(Cu4C22+)Sb4S12S
BaBarium
Ba BaryteBaSO4
Ba Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
OsOsmium
Os Native Iridium(Ir,Os,Ru)
Os Native Osmium(Os,Ir,Ru)
IrIridium
Ir Native Iridium(Ir,Os,Ru)
Ir Native Osmium(Os,Ir,Ru)
Ir Native Ruthenium(Ru,Ir)
PtPlatinum
Pt CooperitePtS
Pt IsoferroplatinumPt3Fe
Pt Native PlatinumPt
Pt TetraferroplatinumPtFe
AuGold
Au Native GoldAu
PbLead
Pb GalenaPbS

Localities in this Region

Other Regions, Features and Areas containing this locality


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.

References

 
and/or  
Mindat.org® is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization. Mindat® and mindat.org® are registered trademarks of the Hudson Institute of Mineralogy.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2026, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph and Ida Chau.
Content on this site may not be used to train, fine-tune, or otherwise develop artificial intelligence or machine learning models without prior written permission - see our Terms & Conditions.
To cite: Ralph, J., Von Bargen, D., Martynov, P., Zhang, J., Que, X., Prabhu, A., Morrison, S. M., Li, W., Chen, W., & Ma, X. (2025). Mindat.org: The open access mineralogy database to accelerate data-intensive geoscience research. American Mineralogist, 110(6), 833–844. doi:10.2138/am-2024-9486.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: September 4, 2026 15:35:31 Page updated: July 27, 2026 01:08:37
Go to top of page