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East Mayacmas Mining District, Lake County, California, USAi
Regional Level Types
East Mayacmas Mining DistrictMining District
Lake CountyCounty
CaliforniaState
USACountry

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PhotosMapsSearchMineralogy
07931600017702294286601.jpg
Serpentine Subgroup, etc.

East Mayacmas Mining District, Lake County, California, USA
04790250017700195717466.jpg
Chrysotile, etc.

East Mayacmas Mining District, Lake County, California, USA
01752680017272093474660.jpg
Idrialite

Great Western Mine, Great Western-Mirabel group, Middletown, East Mayacmas Mining District, Lake County, California, USA
01946200017700202847417.jpg
Serpentine Subgroup, etc.

East Mayacmas Mining District, Lake County, California, USA
04790250017700195717466.jpg
Chrysotile, etc.

East Mayacmas Mining District, Lake County, California, USA
01752680017272093474660.jpg
Idrialite

Great Western Mine, Great Western-Mirabel group, Middletown, East Mayacmas Mining District, Lake County, California, USA
07931600017702294286601.jpg
Serpentine Subgroup, etc.

East Mayacmas Mining District, Lake County, California, USA
04790250017700195717466.jpg
Chrysotile, etc.

East Mayacmas Mining District, Lake County, California, USA
Latitude & Longitude (WGS84):
39° North , 122° West (est.)
Estimate based on other nearby localities or region boundaries.
Margin of Error:
~55km
GRN:
N27W68
Type:
Mining District
Köppen climate type:
Csb : Warm-summer Mediterranean climate
Mindat Locality ID:
80795
Long-form identifier:
mindat:1:2:80795:6
GUID (UUID V4):
0


A Hg mining area located along the Lake County western border with Sonoma County. A portion of the district is located in the NW tip of Napa County.

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

30 valid minerals. 1 erroneous literature entry.

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:

ⓘ Anorthite
Formula: Ca(Al2Si2O8)
Description: Occus as fine cleavage fragments.
ⓘ Aragonite
Formula: CaCO3
Habit: Acicular
Description: Occurs as needle-like crystals and crusts.
ⓘ 'Asbestos'
ⓘ Azurite
Formula: Cu3(CO3)2(OH)2
ⓘ Calcite
Formula: CaCO3
ⓘ Chalcocite
Formula: Cu2S
ⓘ Chalcopyrite
Formula: CuFeS2
Description: Occurs as high-grade ore.
ⓘ Chromite
Formula: Fe2+Cr3+2O4
Localities: Reported from at least 17 localities in this region.
ⓘ Chrysotile
Formula: Mg3(Si2O5)(OH)4
Description: Occurs in serpentine.
ⓘ Cinnabar
Formula: HgS
Localities: Reported from at least 20 localities in this region.
ⓘ 'Clay minerals'
ⓘ Cordierite
Formula: Mg2Al4Si5O18
Colour: Amethystine
Description: Mined for gems. This material was documented as "amethystine quartz" by earlier authors (Averill; Symons); however, Brice later identified the material as cordierite.
ⓘ Dolomite
Formula: CaMg(CO3)2
Description: Occurs well-crystallized as gangue in Hg ores.
ⓘ Epsomite
Formula: MgSO4 · 7H2O
Description: Forms during dry seasons along the margin of a seep at the base of the waste rock pile.
ⓘ Glaucophane
Formula: ◻Na2(Mg3Al2)Si8O22(OH)2
ⓘ Idrialite
Formula: C22H14
ⓘ Jamesonite
Formula: Pb4FeSb6S14
Description: A minor mineral here.
ⓘ 'Limonite'
ⓘ Magnesiochromite
Formula: MgCr2O4
ⓘ Magnesite
Formula: MgCO3
ⓘ Malachite
Formula: Cu2(CO3)(OH)2
ⓘ Marcasite
Formula: FeS2
Description: Occurs in considerable quantities in some ores.
ⓘ Metacinnabar
Formula: HgS
ⓘ Millerite
Formula: NiS
Description: Occurs in very small amounts.
ⓘ Native Mercury
Formula: Hg
Localities: Reported from at least 6 localities in this region.
ⓘ Opal
Formula: SiO2 · nH2O
ⓘ Pectolite
Formula: NaCa2Si3O8(OH)
Description: Occurs as extensive veins of fibrous material with calcite in serpentine.
ⓘ 'Psilomelane'
ⓘ Pyrite
Formula: FeS2
ⓘ Pyrolusite
Formula: Mn4+O2
ⓘ Quartz
Formula: SiO2
Localities: Reported from at least 6 localities in this region.
ⓘ Quartz var. Amethyst
Formula: SiO2
ⓘ Quartz var. Clear Lake Diamond
Formula: SiO2
ⓘ Sassolite
Formula: H3BO3
Description: Occurs as an efflorescence.
ⓘ 'Serpentine Subgroup'
Formula: D3[Si2O5](OH)4
ⓘ Tiemannite
Formula: HgSe
ⓘ Wollastonite
Formula: Ca3(Si3O9)
Colour: White
Description: Material is drusy.

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
ⓘNative Mercury1.AD.05Hg
Group 2 - Sulphides and Sulfosalts
ⓘChalcocite2.BA.05Cu2S
ⓘMetacinnabar2.CB.05aHgS
ⓘTiemannite2.CB.05aHgSe
ⓘChalcopyrite2.CB.10aCuFeS2
ⓘMillerite2.CC.20NiS
ⓘCinnabar2.CD.15aHgS
ⓘPyrite2.EB.05aFeS2
ⓘMarcasite2.EB.10aFeS2
ⓘJamesonite2.HB.15Pb4FeSb6S14
Group 4 - Oxides and Hydroxides
ⓘChromite4.BB.05Fe2+Cr3+2O4
ⓘMagnesiochromite4.BB.05MgCr2O4
ⓘQuartz
var. Amethyst ?		4.DA.05SiO2
ⓘ4.DA.05SiO2
ⓘvar. Clear Lake Diamond4.DA.05SiO2
ⓘOpal4.DA.10SiO2 · nH2O
ⓘPyrolusite4.DB.05Mn4+O2
Group 5 - Nitrates and Carbonates
ⓘCalcite5.AB.05CaCO3
ⓘMagnesite5.AB.05MgCO3
ⓘDolomite5.AB.10CaMg(CO3)2
ⓘAragonite5.AB.15CaCO3
ⓘAzurite5.BA.05Cu3(CO3)2(OH)2
ⓘMalachite5.BA.10Cu2(CO3)(OH)2
Group 6 - Borates
ⓘSassolite6.AA.05H3BO3
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
ⓘEpsomite7.CB.40MgSO4 · 7H2O
Group 9 - Silicates
ⓘChrysotile9.00.Mg3(Si2O5)(OH)4
ⓘCordierite9.CJ.10Mg2Al4Si5O18
ⓘGlaucophane9.DE.25◻Na2(Mg3Al2)Si8O22(OH)2
ⓘPectolite9.DG.05NaCa2Si3O8(OH)
ⓘWollastonite9.DG.05Ca3(Si3O9)
ⓘAnorthite9.FA.35Ca(Al2Si2O8)
Group 10 - Organic Compounds
ⓘIdrialite10.BA.20C22H14
Unclassified
ⓘ'Asbestos'-
ⓘ'Clay minerals'-
ⓘ'Limonite'-
ⓘ'Psilomelane'-
ⓘ'Serpentine Subgroup'-D3[Si2O5](OH)4

List of minerals for each chemical element

HHydrogen
Hⓘ AzuriteCu3(CO3)2(OH)2
Hⓘ ChrysotileMg3(Si2O5)(OH)4
Hⓘ EpsomiteMgSO4 · 7H2O
Hⓘ Glaucophane◻Na2(Mg3Al2)Si8O22(OH)2
Hⓘ IdrialiteC22H14
Hⓘ MalachiteCu2(CO3)(OH)2
Hⓘ OpalSiO2 · nH2O
Hⓘ PectoliteNaCa2Si3O8(OH)
Hⓘ SassoliteH3BO3
Hⓘ Serpentine SubgroupD3[Si2O5](OH)4
BBoron
Bⓘ SassoliteH3BO3
CCarbon
Cⓘ AragoniteCaCO3
Cⓘ AzuriteCu3(CO3)2(OH)2
Cⓘ CalciteCaCO3
Cⓘ DolomiteCaMg(CO3)2
Cⓘ IdrialiteC22H14
Cⓘ MagnesiteMgCO3
Cⓘ MalachiteCu2(CO3)(OH)2
OOxygen
Oⓘ Quartz var. AmethystSiO2
Oⓘ AnorthiteCa(Al2Si2O8)
Oⓘ AragoniteCaCO3
Oⓘ AzuriteCu3(CO3)2(OH)2
Oⓘ CalciteCaCO3
Oⓘ ChrysotileMg3(Si2O5)(OH)4
Oⓘ ChromiteFe2+Cr23+O4
Oⓘ CordieriteMg2Al4Si5O18
Oⓘ DolomiteCaMg(CO3)2
Oⓘ EpsomiteMgSO4 · 7H2O
Oⓘ Glaucophane◻Na2(Mg3Al2)Si8O22(OH)2
Oⓘ MagnesiteMgCO3
Oⓘ MagnesiochromiteMgCr2O4
Oⓘ MalachiteCu2(CO3)(OH)2
Oⓘ OpalSiO2 · nH2O
Oⓘ PectoliteNaCa2Si3O8(OH)
Oⓘ PyrolusiteMn4+O2
Oⓘ QuartzSiO2
Oⓘ SassoliteH3BO3
Oⓘ WollastoniteCa3(Si3O9)
Oⓘ Serpentine SubgroupD3[Si2O5](OH)4
Oⓘ Quartz var. Clear Lake DiamondSiO2
NaSodium
Naⓘ Glaucophane◻Na2(Mg3Al2)Si8O22(OH)2
Naⓘ PectoliteNaCa2Si3O8(OH)
MgMagnesium
Mgⓘ ChrysotileMg3(Si2O5)(OH)4
Mgⓘ CordieriteMg2Al4Si5O18
Mgⓘ DolomiteCaMg(CO3)2
Mgⓘ EpsomiteMgSO4 · 7H2O
Mgⓘ Glaucophane◻Na2(Mg3Al2)Si8O22(OH)2
Mgⓘ MagnesiteMgCO3
Mgⓘ MagnesiochromiteMgCr2O4
AlAluminium
Alⓘ AnorthiteCa(Al2Si2O8)
Alⓘ CordieriteMg2Al4Si5O18
Alⓘ Glaucophane◻Na2(Mg3Al2)Si8O22(OH)2
SiSilicon
Siⓘ Quartz var. AmethystSiO2
Siⓘ AnorthiteCa(Al2Si2O8)
Siⓘ ChrysotileMg3(Si2O5)(OH)4
Siⓘ CordieriteMg2Al4Si5O18
Siⓘ Glaucophane◻Na2(Mg3Al2)Si8O22(OH)2
Siⓘ OpalSiO2 · nH2O
Siⓘ PectoliteNaCa2Si3O8(OH)
Siⓘ QuartzSiO2
Siⓘ WollastoniteCa3(Si3O9)
Siⓘ Serpentine SubgroupD3[Si2O5](OH)4
Siⓘ Quartz var. Clear Lake DiamondSiO2
SSulfur
Sⓘ ChalcopyriteCuFeS2
Sⓘ ChalcociteCu2S
Sⓘ CinnabarHgS
Sⓘ EpsomiteMgSO4 · 7H2O
Sⓘ JamesonitePb4FeSb6S14
Sⓘ MarcasiteFeS2
Sⓘ MetacinnabarHgS
Sⓘ MilleriteNiS
Sⓘ PyriteFeS2
CaCalcium
Caⓘ AnorthiteCa(Al2Si2O8)
Caⓘ AragoniteCaCO3
Caⓘ CalciteCaCO3
Caⓘ DolomiteCaMg(CO3)2
Caⓘ PectoliteNaCa2Si3O8(OH)
Caⓘ WollastoniteCa3(Si3O9)
CrChromium
Crⓘ ChromiteFe2+Cr23+O4
Crⓘ MagnesiochromiteMgCr2O4
MnManganese
Mnⓘ PyrolusiteMn4+O2
FeIron
Feⓘ ChalcopyriteCuFeS2
Feⓘ ChromiteFe2+Cr23+O4
Feⓘ JamesonitePb4FeSb6S14
Feⓘ MarcasiteFeS2
Feⓘ PyriteFeS2
NiNickel
Niⓘ MilleriteNiS
CuCopper
Cuⓘ AzuriteCu3(CO3)2(OH)2
Cuⓘ ChalcopyriteCuFeS2
Cuⓘ ChalcociteCu2S
Cuⓘ MalachiteCu2(CO3)(OH)2
SeSelenium
Seⓘ TiemanniteHgSe
SbAntimony
Sbⓘ JamesonitePb4FeSb6S14
HgMercury
Hgⓘ CinnabarHgS
Hgⓘ Native MercuryHg
Hgⓘ MetacinnabarHgS
Hgⓘ TiemanniteHgSe
PbLead
Pbⓘ JamesonitePb4FeSb6S14

Localities in this Region

USA
USA

Other Regions, Features and Areas containing this locality

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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

Becker, George F. (1888b), Geology of the quicksilver deposits of the Pacific slope: USGS Monograph 13, atlas: 351-362.
Yates, Robert G. & Lowell S. Hilpert (1946), Quicksilver deposits of eastern Mayacmas district, Lake and Napa Counties, California: California Journal of Mines and Geology, California Division of Mines (Report 42): 42: 231-286
White, D.E. (1967) Mercury and base-metal deposits with associated thermal and mineral waters. In: H.L. Barnes (Editor), Geochemistry of hydrothermal ore deposits. Holt Reinhart and Winston, New York: 589
Pemberton, H. Earl (1983) Minerals of California. Van Nostrand Reinhold Company Inc.
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