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⇱ New Almaden Mine (New Almaden Mines), New Almaden, New Almaden Mining District, Santa Clara County, California, USA

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New Almaden Mine (New Almaden Mines), New Almaden, New Almaden Mining District, Santa Clara County, California, USAi
Regional Level Types
New Almaden Mine (New Almaden Mines)Mine
New Almaden- not defined -
New Almaden Mining DistrictMining District
Santa Clara CountyCounty
CaliforniaState
USACountry

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Latitude & Longitude (WGS84):
37° 10' 36'' North , 121° 50' 20'' West
Latitude & Longitude (decimal):
Type:
Nearest Settlements:
PlacePopulationDistance
Lexington Hills2,421 (2011)12.0km
Cambrian Park3,282 (2018)12.0km
Seven Trees1,788 (2018)12.1km
Communications Hill11,267 (2019)12.5km
Los Gatos30,705 (2017)13.2km
Nearest Clubs:
Local clubs are the best way to get access to collecting localities
ClubLocationDistance
Santa Clara Valley Gem & Mineral SocietySan Jose, California19km
Santa Cruz Mineral and Gem SocietySanta Cruz, California28km
Peninsula Gem & Geology Society, Inc.Los Altos, California34km
Sequoia Gem and Mineral SocietyRedwood City, California49km
Mindat Locality ID:
3516
Long-form identifier:
mindat:1:2:3516:6
GUID (UUID V4):
0


A former Hg occurrence/mine complex located in secs. 2 & 3, T9S, R1E, and in secs. 29 & 33, T8S, R1E, MDM. The peak of Mine Hill (527 meters (1730 ft.) AMSL) above the main mine workings is 2.1 km (1.4 mile) N92.4W of center of Casa Grande manor house in New Almaden and about 17 km (11 miles) N166.7E from old downtown main post office (now art museum) in San Jose. The former mine is on land owned by Santa Clara County and open to the public as Almaden Quicksilver County Park. First worked in prehistorical times by indigenous peoples to collect cinnabar to make vermillion paint. The peoples introduced the ore and vermillion paint to 18th-Century settlers at Mission Santa Clara de Asís. Antonio Suñol and Louis Chaboya tried unsuccessfully to identify the ore in 1824 and are credited with the "discovery" of the mine. Claimed by Andrés Castillero in late-1845. Small quantities of mercury were produced from ore starting at this time. MRDS database stated accuracy for this location is 1,000 meters. The property was sold by New Idria Mining and Chemical Company to the County in parcels, with the final parcel (Mine Hill) transferred in mid-1975.

Principle geological descriptions of the mine pre-date modern theory of plate tectonics. Bailey and Everhart (1964) is by far the best and most thorough description. Mineralization is a Hg deposit primarily hosted in Late Cretaceous serpentinite and tuffaceous rocks metasomatized to so-called silica-carbonate rock. The shallower central mine workings under Mine Hill (called the main mine) are irregular and strike N-S to N15E to a depth of about 244 meters (800 ft.) below the peak. The two deeper ore bodies (North and South Randol (misnomer, respectively east and west)) trend N25W and dip at about a 45-degree angle to a maximum depth of about 610 meters (2000 ft.) below the peak of Mine Hill (formerly 535 meters (1755 ft.) AMSL, now 527 meters (1730 ft.) AMSL). The deepest exploratory working is the Church shaft sump and drift on the 750 meter (2450 ft.) level below the former peak of Mine Hill. The ore bodies are primarily cinnabar replacement in fractured silica-carbonate rock surrounded by sedimentary rocks of the Jurassic-Cretaceous Franciscan complex. Rock contacts are highly sheared and irregular. Ore bodies generally conform to the silica-carbonate replacement of serpentinite thought to be intrusive into the Franciscan rocks, but now known to be structures associated with older subduction processes then complicated (dissected) by dextral faulting associated with the still-active San Andreas fault system. The primary mode of origin was hydrothermal activity related to crustal thinning in the wake of the northward migration of the Mendocino Triple Junction about 14.5 Ma. Primary ore control was lithology (serpentinite contact) and the secondary control was fracturing. Wallrock alteration is moderate (carbonitization). Associated with Upper Cretaceous rocks of the Santa Teresa Hills. Local rocks include rocks of the Franciscan Complex, unit 1 (Coast Ranges).

Local geologic structures include a local anticline and tension fractures. Regional structure is NW-trending.

Workings include surface and underground openings with a length of 53,106.9 meters and an overall depth of 746.76 meters (cumulative all mines).

Production to the end of 1976 was 38,090,000 kilograms (1,104,922 flasks) of Hg from 1,722,900 tonnes of ore. The average 5 year annual grade was 5.40% and the cumulative grade was 2.21%. Production for the group was more than 1,000,000 flasks of Hg, most from this mine.

Estimates of hypothetical resources range from 100,000 to 1,000,000 flasks of Hg.

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


16 valid minerals. 1 (FRL) - first recorded locality of unapproved mineral/variety/etc.

Rock Types Recorded

Note: data is currently VERY limited. Please bear with us while we work towards adding this information!

Select Rock List Type

Alphabetical List Tree Diagram

Entries shown in red are rocks recorded for this region.

Detailed Mineral List:

ⓘ 'Apophyllite Group'
Formula: AB4[Si8O22]X · 8H2O
Description: Well-developed crystals line crevices in rock.
ⓘ 'Aragotite' (FRL)
Formula: (C,H)
Type Locality:
Description: Impregnates siliceous dolomite.
ⓘ Arsenopyrite
Formula: FeAsS
Description: Minor amounts occur in Hg ore. Bailey & Everhart question this occurrence.
ⓘ Calcite
Formula: CaCO3
ⓘ Chalcopyrite
Formula: CuFeS2
ⓘ Cinnabar
Formula: HgS
ⓘ Dolomite
Formula: CaMg(CO3)2
Description: Occasionally occrs in veins in ore.
ⓘ Epsomite
Formula: MgSO4 · 7H2O
Description: Abundant on mine walls as a post-mining product.
ⓘ Galena
Formula: PbS
Description: A little occurs in ores.
ⓘ Gyrolite
Formula: NaCa16Si23AlO60(OH)8 · 14H2O
ⓘ Jarosite
Formula: KFe3+3(SO4)2(OH)6
ⓘ Metacinnabar
Formula: HgS
Habit: Hexagonal, with complex forms
ⓘ Millerite
Formula: NiS
Description: Occurs in Hg ores.
ⓘ Native Mercury
Formula: Hg
Description: Small amounts occur here.
ⓘ Opal
Formula: SiO2 · nH2O
ⓘ 'Petroleum var. Bitumen'
ⓘ Pyrite
Formula: FeS2
Habit: Prismatic, slender
ⓘ Quartz
Formula: SiO2
ⓘ Quartz var. Chalcedony
Formula: SiO2
ⓘ 'Serpentine Subgroup'
Formula: D3[Si2O5](OH)4
ⓘ Stibnite
Formula: Sb2S3

Gallery:

HgSⓘ Cinnabar

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
ⓘNative Mercury1.AD.05Hg
Group 2 - Sulphides and Sulfosalts
ⓘMetacinnabar2.CB.05aHgS
ⓘChalcopyrite2.CB.10aCuFeS2
ⓘMillerite2.CC.20NiS
ⓘGalena2.CD.10PbS
ⓘCinnabar2.CD.15aHgS
ⓘStibnite2.DB.05Sb2S3
ⓘPyrite2.EB.05aFeS2
ⓘArsenopyrite2.EB.20FeAsS
Group 4 - Oxides and Hydroxides
ⓘQuartz
var. Chalcedony		4.DA.05SiO2
ⓘ4.DA.05SiO2
ⓘOpal4.DA.10SiO2 · nH2O
Group 5 - Nitrates and Carbonates
ⓘCalcite5.AB.05CaCO3
ⓘDolomite5.AB.10CaMg(CO3)2
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
ⓘJarosite7.BC.10KFe3+3(SO4)2(OH)6
ⓘEpsomite7.CB.40MgSO4 · 7H2O
Group 9 - Silicates
ⓘGyrolite9.EE.30NaCa16Si23AlO60(OH)8 · 14H2O
Unclassified
ⓘ'Apophyllite Group'-AB4[Si8O22]X · 8H2O
ⓘ'Aragotite' (TL)-(C,H)
ⓘ'Petroleum
var. Bitumen'		-
ⓘ'Serpentine Subgroup'-D3[Si2O5](OH)4

List of minerals for each chemical element

HHydrogen
Hⓘ Apophyllite GroupAB4[Si8O22]X · 8H2O
Hⓘ Aragotite(C,H)
Hⓘ EpsomiteMgSO4 · 7H2O
Hⓘ GyroliteNaCa16Si23AlO60(OH)8 · 14H2O
Hⓘ JarositeKFe33+(SO4)2(OH)6
Hⓘ OpalSiO2 · nH2O
Hⓘ Serpentine SubgroupD3[Si2O5](OH)4
CCarbon
Cⓘ Aragotite(C,H)
Cⓘ CalciteCaCO3
Cⓘ DolomiteCaMg(CO3)2
OOxygen
Oⓘ Apophyllite GroupAB4[Si8O22]X · 8H2O
Oⓘ CalciteCaCO3
Oⓘ Quartz var. ChalcedonySiO2
Oⓘ DolomiteCaMg(CO3)2
Oⓘ EpsomiteMgSO4 · 7H2O
Oⓘ GyroliteNaCa16Si23AlO60(OH)8 · 14H2O
Oⓘ JarositeKFe33+(SO4)2(OH)6
Oⓘ OpalSiO2 · nH2O
Oⓘ QuartzSiO2
Oⓘ Serpentine SubgroupD3[Si2O5](OH)4
NaSodium
Naⓘ GyroliteNaCa16Si23AlO60(OH)8 · 14H2O
MgMagnesium
Mgⓘ DolomiteCaMg(CO3)2
Mgⓘ EpsomiteMgSO4 · 7H2O
AlAluminium
Alⓘ GyroliteNaCa16Si23AlO60(OH)8 · 14H2O
SiSilicon
Siⓘ Apophyllite GroupAB4[Si8O22]X · 8H2O
Siⓘ Quartz var. ChalcedonySiO2
Siⓘ GyroliteNaCa16Si23AlO60(OH)8 · 14H2O
Siⓘ OpalSiO2 · nH2O
Siⓘ QuartzSiO2
Siⓘ Serpentine SubgroupD3[Si2O5](OH)4
SSulfur
Sⓘ ArsenopyriteFeAsS
Sⓘ ChalcopyriteCuFeS2
Sⓘ CinnabarHgS
Sⓘ EpsomiteMgSO4 · 7H2O
Sⓘ GalenaPbS
Sⓘ JarositeKFe33+(SO4)2(OH)6
Sⓘ MetacinnabarHgS
Sⓘ MilleriteNiS
Sⓘ PyriteFeS2
Sⓘ StibniteSb2S3
KPotassium
Kⓘ JarositeKFe33+(SO4)2(OH)6
CaCalcium
Caⓘ CalciteCaCO3
Caⓘ DolomiteCaMg(CO3)2
Caⓘ GyroliteNaCa16Si23AlO60(OH)8 · 14H2O
FeIron
Feⓘ ArsenopyriteFeAsS
Feⓘ ChalcopyriteCuFeS2
Feⓘ JarositeKFe33+(SO4)2(OH)6
Feⓘ PyriteFeS2
NiNickel
Niⓘ MilleriteNiS
CuCopper
Cuⓘ ChalcopyriteCuFeS2
AsArsenic
Asⓘ ArsenopyriteFeAsS
SbAntimony
Sbⓘ StibniteSb2S3
HgMercury
Hgⓘ CinnabarHgS
Hgⓘ Native MercuryHg
Hgⓘ MetacinnabarHgS
PbLead
Pbⓘ GalenaPbS

Other Regions, Features and Areas containing this locality

North AmericaContinent
North America PlateTectonic Plate
USA

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