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Hermosa Mine

Past Producer in Santa Cruz county in Arizona, United States with commodities Silver, Manganese, Lead, Copper, Gold, Molybdenum
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Public Land Survey System information
  6. Commodities
  7. Materials information
  8. Alteration
  9. Host and associated rocks
  10. Nearby scientific data
  11. Geologic structures
  12. Ore body information
  13. Controls for ore emplacement
  14. Economic information about the deposit and operations
  15. Mining district
  16. Land status
  17. Ownership information
  18. Production statistics
  19. Workings at the site
  20. Links to other databases
  21. Bibliographic references
  22. General comments
  23. Reporter information

Geologic information

Identification information

Deposit ID 10037094
MRDS ID M030389
Record type Site
Current site name Hermosa Mine
Related records 10186321

Geographic coordinates

Geographic coordinates: -110.70917, 31.45611 (WGS84)
Elevation 1646
Relative position 3/4 MI S OF HARSHAW ON AMERICAN PEAK.

Site location context

Political divisions (FIPS codes)

Santa Cruz(county)

Arizona(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Harshaw(quadrangle 1:24,000 scale)

Nogales(quadrangle 1:100,000 scale)

Nogales(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Upper Santa Cruz(hydrologic unit)

Santa Cruz(hydrologic accounting unit)

Middle Gila(hydrologic subregion)

Lower Colorado(hydrologic region)

Federal lands

Coronado National Forest(National Forest)

National Forest FS(Type of land area)

FS(Federal land areas administered by FS)

Geographic areas

Country State County
United States Arizona Santa Cruz

Public Land Survey System information

Meridian Township Range Section Fraction State
Gila and Salt River 023S 016E 4 SE Arizona

Comments on the location information

  • LOCATED INCORRECTLY BY USGS ON TOPO SHEET. IT IS REALLY SE OF WHERE SHOWN;. INFO FROM LAND.ST :1979
  • From Wildcat Silver's website: The Hermosa project is located about 80 kilometres southeast of Tucson, Arizona, and is about 13 kilometres north of the U.S. border with Mexico. Wildcat land holdings now consist of patented mining claims totalling about 154 acres and unpatented mining claims totalling approximately 6,000 acres. Hermosa is located in the Patagonia Mountains that form the western edge of the Mexican Highland section of the Basin and Range Physiographic Province of the southwest United States, with a prominent northwest-trending structural grain. Elevations in the area range up to about 2,800 metres above sea level, the Property is situated at about 1,600 metres above sea level.

Commodities

Commodity Importance
Silver Primary
Manganese Critical Primary
Lead Tertiary
Copper Tertiary
Gold Tertiary
Molybdenum Tertiary

Materials information

Materials Type of material
Cerargyrite Ore
Hematite Gangue
Limonite Gangue
Psilomelane Gangue

Alteration

  • (Local) Oxidized Extensively

Host and associated rocks

  • Host or associated Associated
    Rock type Plutonic Rock > Ultramafic Intrusive Rock > Pyroxenite
    Stratigraphic age (youngest) Late Jurassic
    Stratigraphic age (youngest) Late Cretaceous
  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic) > Felsic Volcanic Rock > Rhyolite

Nearby scientific data

(1) -110.70917, 31.45611
ListMap

Economic information

Geologic structures

Type of structure Local
Structure description Deposit Occurs In More Or Less Tabular Sheet Contained In Fault Breccia Zone
Type of structure Regional
Structure description Rhyolite Is Crushed, Recemented, And Locally Closely Banded By Flow Structure

Ore body information

  • General form IRREGULAR, TABULAR
    Dip 33 N
    Width 6.1M

Controls for ore emplacement

  • High Grade Silver Chloride Pockets In Fracture Fillings And Replacements Of Jur Rhyolite And Latite Porphyry Breccia Along A Fault Zone

Comments on the geologic information

  • From Wildcat Silver's website: The Hermosa deposit is contained within a series of Cretaceous ash flow tuffs and breccias that were deposited upon gently north-dipping Permian-age Concha Formation limestone, and Scherrer Formation dolomite and sandstone. The deposit is located in and above a series of Paleozoic horst blocks that were active during Cretaceous volcanism. The Cretaceous-age tuffs and breccias are thinner over the Hermosa deposit than to the east and west where the tuffs and breccias rest conformably upon ignimbritic cooling units. Post-ash flow feeder dikes to thick trachyandesite flows that once completely covered the deposit area intrude some of the bounding blocks of the horst. The major lithologic host for the Hermosa deposit is an epiclastic sandstone that is locally interbedded with very fine-grained tuff. High-angle faults, trending predominantly north-south and east-west, bound the horst blocks in the area, and may have served as conduits for mineralizing fluids. Sections through the deposit oriented both east-west and north-south suggest that the strata are deformed into a doubly-plunging anticline the apex of which is coincident with the highest grade-thickness of silver accumulation, which suggests that deformation pre-dated the mineralizing event, that mineralizing fluids migrated to the topographically highest permeable area, and that post-mineral tilting of the deposit has occurred.

Economic information about the deposit and operations

Development status Past Producer
Commodity type Metallic
Deposit size Small
Significant No
Discovery year 1877
Year of first production 1878
Year of last production 1950
Production years 1896-1964

Mining district

District name Harshaw District

Land status

Ownership category National Forest
Area name Coronado National Forest

Ownership information

  • Type Owner
    Owner Grover Marsteller )
    First year 1950
  • Type Unknown
    Owner ASARCO
    Year 2013
    Last year 1996
  • Type Unknown
    Owner Wildcat Silver
    Home office Executive Office 4500 Cherry Creek Sourh Drive, Suite 1040 Denver, CO 80246
    Year 2013
    First year 1996

Production statistics

  • Year 1950
    Period 1870-1950
    Material ORE
    Accuracy Estimate
    Description Cp_Grade: ^20 Oz/T Ag
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Ore Silver Silver 565g/mt

Comments on the production information

  • PRODUD IN 1870'S-1900, 1908, 1949-50; FROM 1880-1930 PRODUCED $1 MILLION IN SILVER.
  • Production from 1896-1964 totaled 32,000 tonnes with average grade 250 grams per tonne of silver. (Wildcat Silver's website, http://www.wildcatsilver.com/hermosa-project/history/default.aspx).

Workings at the site

  • Type of workings Underground
    Length 2133.6M
    Overall depth 152.4M

Comments on the workings information

  • INCLINED SHAFT AND TUNN WORKINGS; 5 LEVELS 50 FT APART VERTICALLY.

Comments on development

  • PREVIOUS OWNERS INCLUDE HERMOSA MINING CO, PRIETUS MINES CO, FINLEY, HERMOSA MINING AND MILLING CO, JAMES COCHRAN (06), A.R. BYRD (1941), E. BOLINGER

Reference information

Bibliographic references

  • Deposit

    KEITH, 1975, ABM BULL 191.

  • Deposit

    ELSING AND HEINEMAN, 1936, ABM BULL 140.

  • Deposit

    SCHRADER, 1915, USGS BULL 582.

  • Deposit

    ABGMT CLIPPINGSILE, HERMOSA MINE.

  • Deposit

    ABGMT FILES, STANTON B. KEITH.

  • Deposit

    ABGMT-USBM FILE DATA.

  • Deposit

    ABGMT

  • Deposit

    USGS

  • Production

    KEITH, 1975; ELSING AND HEINEMAN, 1936

  • Deposit

    Wilburn, D.R., and Stanley, K.A., 2013, Exploration Review: Mining Engineering, v. 65, no. 5, p. 39.

  • Deposit

    Wildcat Silver Corp., 2013, Hermosa Project: Accessed May 17, 2013 at http://www.wildcatsilver.com/hermosa-project/overview/default.aspx.

  • Deposit

    Snider, Joshua, 2012, Hermosa Project, Santa Cruz County, Arizona, Preliminary Economic Assessment Form 43-101F1 Technical Report, 162 p. [download 2012 Hermosa PEA (43-101) from http://www.wildcatsilver.com/hermosa-project/metallurgy/default.aspx.]

General comments

Subject category Comment text
General Quotes from Wildcat Silver's website: The Hermosa deposit was discovered in 1879. Production from this and neighbouring workings was carried out between 1896 and 1964 and amounted to about 32,000 tonnes with an average grade of about 250 grams per tonne of silver. Asarco operated the nearby Trench mine between 1939 and 1964. The Hermosa property was first used as a source of water for the Trench mill, and then explored by Asarco by surface geological mapping and intermittent drill programs from 1964 until about 1980. In total, 104 percussion and core holes were drilled, with an aggregate length of 13,088 metres. A mineral inventory calculated by Asarco in 1984 estimated a resource of 8.7 million tonnes with an average grade of 215 grams per tonne silver. Cutoff was inferred to be 47 grams per tonne silver.* Arizona Minerals, which is 80% owned by Wildcat Silver, acquired the property from Asarco in 1996. *These historical figures were defined in a report published by ASARCO in 1984, and were later discussed in a Technical Report published by Wardrop Engineering Inc. dated May 6, 2005. Wildcat has not done the work necessary to verify he classification of the resource and is not treating the resource figure as a NI 43-101 defined resource verified by a qualified person at this time, and therefore should not be relied upon by investors.
Deposit THIS REPORT WAS TAKEN FROM RECORD M030389 OF JAN WILT IN MOLYBDENUM FILE, CONTACT PERSON T.G. THEODORE, USGS. ; 2 UNPUB REPT

Reporter information

Type Date Name Affiliation Comment
Reporter 1983-05-01 Peterson, Jocelyn A. U.S. Geological Survey
Updater 1982-03-01 Calder, Susan R. U.S. Geological Survey
Updater 2013-05-17 Wilson, Anna B U.S. Geological Survey

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Current status (per MSHA)

StatusNonProducing since 01/27/2021
MSHA mine ID0203398
Mine name (MSHA)Hermosa Mine
Current operatorSouth32 Hermosa Inc.
Current controller (parent)South32
Mine typeUnderground (Metal / non-metal)

Inferred by coordinate + name similarity (1688 m, 1.00 match). Confirm against MSHA if precision matters — non-USGS-curated cross-references may occasionally point at a neighbouring mine.

Open MSHA's Mine Data Retrieval System for inspections, accidents, and violations for this mine.

Operator history (post-MRDS)

MRDS records operators as of each record's last update (≤ 2019). Some of the operators listed here have since changed hands or dissolved:

  • ASARCO — acquired by Asarco LLC, subsidiary of Grupo México (2009)
    American Smelting and Refining Co. Filed Chapter 11 in 2005; acquired out of bankruptcy by Grupo México in 2009.

Curated by qvyshift.com from publicly-reported M&A activity (SEC filings, press releases, USGS Mineral Yearbooks). Not authoritative — verify against primary sources before relying on it. The MSHA panel above is the current authoritative source for actively-permitted mines.

External references

Maps centered on this site

Authoritative Arizona resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.