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New Cornelia Ajo

Past Producer in Pima county in Arizona, United States with commodities Copper, Gold, Molybdenum, Silver, Zinc, Gemstone, Semiprecious Gemstone, Rubidium, Titanium, Niobium (Columbium), Iron
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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. Mineral occurrence model information
  10. Host and associated rocks
  11. Nearby scientific data
  12. Geologic structures
  13. Ore body information
  14. Controls for ore emplacement
  15. Economic information about the deposit and operations
  16. Mining district
  17. Mineral rights holdings
  18. Land status
  19. Ownership information
  20. Production statistics
  21. Reserves and resources
  22. Workings at the site
  23. Links to other databases
  24. Bibliographic references
  25. General comments
  26. Reporter information

Geologic information

Identification information

Deposit ID 10283204
MRDS ID M002273
MAS/MILS ID 0040190008
Record type Deposit
Current site name New Cornelia Ajo
Alternate or previous names New Cornelia Mine, Ajo Mine

Geographic coordinates

Point of reference Ore Body
Geographic coordinates: -112.86854, 32.354 (WGS84)
Elevation 550
Location accuracy 100(meters)

Site location context

Political divisions (FIPS codes)

Pima(county)

Arizona(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Ajo South(quadrangle 1:24,000 scale)

Ajo(quadrangle 1:100,000 scale)

Ajo(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Tenmile Wash(hydrologic unit)

Lower Gila(hydrologic accounting unit)

Lower Gila(hydrologic subregion)

Lower Colorado(hydrologic region)

Geographic areas

Country State County
United States Arizona Pima

Public Land Survey System information

Meridian Township Range Section Fraction State
Gila and Salt River 012 S 006 W 27 Arizona

Commodities

Commodity Importance
Copper Primary
Gold Secondary
Molybdenum Secondary
Silver Secondary
Zinc Critical Secondary
Gemstone Secondary
Semiprecious Gemstone Secondary
Rubidium Critical Tertiary
Titanium Critical Tertiary
Niobium (Columbium) Critical Tertiary
Iron Tertiary

Comments on the commodity information

  • Carbonate Ore Is Mined Out, Only Sulfide Ore Remains. This Mine Is A Notable Locality For The Massive Deep Blue Shattuckite (A Hydrous Copper Silicate).

Materials information

Materials Type of material
Bornite Ore
Chalcocite Ore
Chalcopyrite Ore
Chrysocolla Ore
Gold Ore
Malachite Ore
Molybdenite Ore
Silver Ore
Covellite Ore
Hematite Ore
Ilmenite Ore
Magnetite Ore
Pyrite Ore
Rutile Ore
Shattuckite Ore
Tenorite Ore
Kaolin Gangue
Quartz Gangue
Talc Gangue

Alteration

  • (Local) Sericitic, Clay, Chloritization, Kaolinization, Silicification
  • (Local) Oxidized Down to Water Table

Analytical data

Result 1928: 1.13% CU, 0.091 OZ/T AG, 0.006 OZ/T AU
Result MOO3 IS ESTIMATED AT LESS THAN 0.1%. RUTILE OCCURS AS EQUANT GRAINS OVER 20 MICRONS AT ROUGHLY 0.1% IN K-FELDSPAR. RUTILE IS HIGH IN NB.

Mineral occurrence model information

Model code 53
USGS model code 17
Deposit model name Porphyry Cu
Mark3 model number 4

Host and associated rocks

  • Host or associated Host
    Rock type Plutonic Rock > Granitoid > Quartz Monzonite
    Rock unit name Chico Shuni (Cornelia)
    Stratigraphic age (youngest) Paleocene
  • Host or associated Associated
    Rock type Plutonic Rock > Granitoid > Quartz Monzonite
    Rock unit name Cornelia Pluton
    Stratigraphic age (youngest) Paleocene
  • Host or associated Host
    Rock type Unconsolidated Deposit > Alluvium
    Rock unit name Locomotive Fanglomerate
  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic)

Nearby scientific data

Ore Body (1) -112.86854, 32.354
ListMap

Economic information

Geologic structures

Type of structure Local
Structure name NNW Fracture Zones, A Number of Major Faults With Large Displacements
Type of structure Local
Structure name Fanglomerate and Volcanics Are Steeply Dipping

Ore body information

  • Thickness 275M
    Length 2100M
    Width 1250M
    Depth to top 20M
    Field Value
    MAS Matrix # 1
    MAS Column # 1
    Type of Orebody #1 STOCKWORK
    Shape of Orebody #1 MASSIVE
    Type of Orebody #2 DISSEMINATED
    Primary mode of Origin HYDROTHERMAL
    Secondary mode of Origin OXIDATION
    Primary Ore Control FAULTING
    Secondary Ore Control LITHOLOGY
    Degree of Wallrock Alter. MODERATE
    Type of Wallrock Alter. #1 SERICITIC
    Type of Wallrock Alter. #2 SILICIFICATION
    Type of Wallrock Alter. #3 INTERM ARGILLIC
    Minimum Depth to Top 0
    Avg. Thick. Unconsol. Mat. 20
    Min. Thick. Unconsol. Mat. 0
    Date of Last Modification 830615
  • Area 1425HA
    Field Value
    Total Surface Area (HA) 1425
    Date of Last Modification 910418
  • Name Elliptical
    Thickness 304.8M
    Length 2011.63M
    Width 1206.98M
    Depth to top 0M
    Depth to bottom 487.68M
  • Name Lenticular, Erratic
    Strike WNW
    Dip S

Controls for ore emplacement

  • Fracturing of Porphyry

Comments on the geologic information

  • Contact Of Oxidized And Sulfide Ore Is Sharp. There Is No Leached Overburden. Gold Is More Closely Associated With Copper Sulfides Than With Pyrite. Units Present Include Quartz Monzonite, Quartz Diorite, Granodiorite, Equigranular Quartz Monzonite, Porphyritic Quartz Monzonite, Porphyritic Micro Quartz Monzonite.

Economic information about the deposit and operations

Operation type Surface
Development status Past Producer
Commodity type Metallic
Deposit size Large
Significant Yes
Discovery year 1750
Discoverer Spainards
Mining method Open Pit
Year of first production 1917
Year of last production 1985
Milling method Flotation

Mining district

District name Ajo District

Mineral rights holdings

Type of mineral rights Patented
Type of mineral rights Fee Ownership

Land status

Ownership category Private

Ownership information

  • Type Owner-Operator
    Owner Phelps Dodge Corp, 2600 N Central Ave, Phoenix, Az 85004
    ID 200156
    Interest 100
    Home office Arizona
    Year 1987
  • Type Operator
    Owner J.B. Johnson
    First year 1917

Production statistics

  • Year 1913
    Accuracy Estimate
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary Ore Copper Copper 2wt-pct
  • Year 1957
    Period 1917-1957
    Accuracy Estimate
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary Ore Copper Copper 1wt-pct
  • Year 1962
    Period 1917-1962
    Ore mined 255000000mt
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary Cu Copper Copper 1wt-pct
  • Year 1973
    Period 1970-1973
    Accuracy Estimate
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary Copper Copper 1wt-pct
  • Year 1977
    Description Total Ore Mined 6194050 Metric Tons For The Year
  • Year 1978
    Description Total Ore Mined 7696820 Metric Tons For The Year
  • Year 1979
    Description Total Ore Mined 9241320 Metric Tons For The Year
  • Year 1980
    Description Total Ore Mined 6387280 Metric Tons For The Year
  • Year 1981
    Description Total Ore Mined 8715680 Metric Tons For The Year
  • Year 1981
    Period 1917-1981
    Ore mined 390000000mt
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary Cu Copper Copper 1wt-pct
    Secondary Ag Silver Silver 2wt-pct
    Secondary Au Gold Gold 0g/mt
    Secondary Mo Molybdenum Molybdenum 0wt-pct
  • Year 1982
    Description 70 Mt Mo Prod From Ore
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Minor Molybdenum Molybdenum 70mt
  • Year 1982
    Description 9641 Mt Cu Prod From Ore
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Major Ore Copper Copper 9641mt
  • Year 1982
    Description 300 Mt Cu Prod From Ppt
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Major Copper Copper 300mt
  • Year 1982
    Description Mine Closed 4/82 - Cu Prices Depressed 1862000 Mt Ore Mined
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Major Ore Copper Copper 1862000mt
  • Year 1983
    Description No Leach Ppt Cu Produced No Cu Ppt Produced
  • Year 1983
    Description 72 Mt Mo Produced
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Minor Molybdenum Molybdenum 72mt
  • Year 1983
    Description Shutdown Without Production In Jan + Feb 7278000 Mt Ore Mined
  • Year 1983
    Description 33838 Mt Cu Produced
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Major Copper Copper 33838mt
  • Year 1984
    Description 91 Mt Mo Produced
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Minor Molybdenum Molybdenum 91mt
  • Year 1984
    Description 417 Mt Cu Prod From Ppt
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Major Copper Copper 417mt
  • Year 1984
    Description 21610 Mt Cu Prod From Ore
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Major Ore Copper Copper 21610mt
  • Year 1984
    Description Mine Shutdown Indefinitely In Aug 1984 5255000 Mt Ore Mined
  • Year 1985
    Description 182 Mt Cu Prod Frm Dump Leach
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Major Copper Copper 182mt
  • Year 1985
    Period 1911-1985
    Ore mined 418800000mt
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary Cu Copper Copper 2803000mt
    Secondary Ag Silver Silver 692mt
    Secondary Au Gold Gold 58mt
    Secondary Mo Molybdenum Molybdenum 420mt

Comments on the production information

  • Also Known As Ajo. Reserves Reported From Phelps Dodge Corp. 12/31/94. P. 14. 1982-1985 Production Taken From (1) Primary Copper Industry Of Arizona Special Repts Nos 6,8 & 9. Az Dept Of Mines & Min. Res. & (2) Phelps Dodge 1986 Ann Rept. P. 8. Mine Closed For Indefinite Period In Aug 1984. 1986 Ann Rept Stated That Mine Will Not Reopen Until Cu Price Rises Above 80 Cents Per Lb. (P. 9.)

Reserves and resources

  • Type In-situ
    Name milling material
    Estimate year 2009
    Demonstrated 639000000mt
    Remarks Freeport-McMoRan 2009 10K, p. 40. \nhttp://www.fcx.com/ir/downloads/FCX_2009Form_10-K.pdf
    Commodity Subtype Grade units Group Importance Year
    Copper 0.36 wt-pct Copper Primary 2009
    Gold 0.07 g/mt Gold Secondary 2009
    Silver 0.9 g/mt Silver Secondary 2009
    Molybdenum 0.007 wt-pct Molybdenum Secondary 2009
  • Type In-situ
    Estimate year 2008
    Total endowment 742000000mt ore
    Remarks Singer 2008.
    Commodity Subtype Grade units Group Importance Year
    Copper Cu 0.576 wt-pct Copper Primary 2008
    Silver 1.7 g/mt Silver Secondary 2008
    Gold 0.16 g/mt Gold Secondary 2008
    Molybdenum 0.0089 wt-pct Molybdenum Secondary 2008
  • Type In-situ
    Estimate year 1998
    Total resources 580000000mt ore
  • Type In-situ
    Estimate year 1994
    Indicated 145000000mt ore
    Demonstrated 145000000mt ore
    Total resources 145000000mt ore
    Commodity Subtype Grade units Group Importance Year
    Copper Cu 0.56 wt-pct Copper Major 1994
  • Type In-situ
    Estimate year 1932
    Total resources 90702000mt ore
  • Type In-situ
    Estimate year 1984
    Total resources 189800000mt ore
    Remarks Contains 950,000 mt of Cu
  • Type In-situ
    Estimate year 1996
    Demonstrated 145150000mt ore
    Total resources 145150000mt ore
    Commodity Subtype Grade units Group Importance Year
    Copper Cu 0.5 wt-pct Copper Major 1996

Comments on the reserve resource information

  • Also Known As Ajo. Reserves Reported From Phelps Dodge Corp. '94. P. 14.

Workings at the site

  • Type of workings Surface
    Area 267HA
    Field Value
    MAS Development Schedule # 1
    Mining Record # 1
    Status of Mining Method ESTIMATE
    Mining Method OPEN PIT
    Swell Factor .75
    Percent Waste Rock 53
    Avg. Overburden Thickness 20
    Primary Material Cover M-HARD ROCKS
    Hardness of Ore HARD ROCKS
    Avg. Bench Height (meters) 12
    Max. Pit Slope (degrees) 45
    Capacity 25266
    Capacity Units MT ORE/DAY
    Unit Production Cost 2.67
    Units of Production $/MT ORE
    Operating Days per Year 340
    Operating Shifts per Day 3
    Year of Information 1982
  • Type of workings Surface/Underground
    Overall depth 24.38M
  • Type of workings Surface
    Length 1371.6M
    Overall depth 1524M

Comments on the workings information

  • Shallow Workings; Drilling To 1000 Ft In 1919 To 1921 Located No Further Ore.

Reference information

Bibliographic references

  • Development

    The Metals Economics Group (MEG) webpage for the Ajo Mine contains information about this deposit. Accessed on 8/17/2010.
    http://www.metalseconomics.com/

  • Other Database

    CIMRI

  • Deposit

    WORLD MINING. SEPT. 1981, P. 50, & SEPT. 1982, P. 70. (1977-1981 PRODUCTION)

  • Geology

    Hagstrum J T, Cox D P, Miller R J 1987 - Structural reinterpretation of the Ajo mining district, Pima County, Arizona, based on paleomagnetic and geochronologic studies: in Econ. Geol. v82 pp 1348-1361

  • Reserve-Resource

    Porter, T.M., 1998, An overview of the World's porphyry and other hydrothermal copper & gold deposits and their distribution; in Porter, T. M., ed., Porphyry and Hydrothermal Copper and Gold Deposits: a global perspective, PACRIM '98 Conference Proceedings, Australian Mineral Foundation, p. 3-17.

  • Reserve-Resource

    Damon, P.E. and Mauger, R.L., 1966, Epeirogeny-orogeny viewed from the Basin and Range Province; Society of Mining Engineers, AIME Transactions, v. 235, p. 99-112.

  • Geology

    The Porter GeoConsultancy webpage for Ajo, New Cornelia contains a description of the geology. Accessed on 8/17/2010.
    http://www.portergeo.com.au/

  • Deposit

    GILLULY, 1946, USGS PP 209.

  • Deposit

    DIXON, 1966, IN TITLEY & HICKS, UNIV OF AZ PRESS, P. 123-132.

  • Reserve-Resource

    PHELPS DODGE CORP SEC FORM 10-K REPT. DEC 31, 1993. P. 14.

  • Deposit

    BELL, 1930, USBM IC 6303.

  • Reserve-Resource

    PHELPS DODGE CORP 1995 ANNUAL REPORT, P.23.

  • Reserve-Resource

    Phelps Dodge 1984 SEC Form 10K

  • Deposit

    GEOLOGY OF THE PORPHYRY COPPER DEPOSITS SOUTHWESTERN NORTH AMERICA BY TITLY AND HICKS, 1966.

  • Reserve-Resource

    GILMOUR, P., 1982, GRADES AND TONNAGES OF PORPHYRY COPPER DEPOSITS: IN - ADVANCES IN GEOLOGY OF THE PORPHYRY COPPER DEPOSITS, SOUTHWESTERN NORTH AMERICA, ED. BY, S.R. TITLEY UNIV. AIR. PRESS, TUCSON, AZ, 1982.

  • Deposit

    HARDWICK, 1960, USBM IC 7938.

  • Deposit

    MINING METHODS AND COSTS AT THE NEW CORNELIA BRANCH, PHELPS DODGE CORPORATION, AJO, ARIZ.-U.S.B.M. I.C. 6666,OCT,1932

  • Deposit

    WADSWORTH, 1968, ECON GEOL, V. 63, NO. 2.

  • Deposit

    ARIZONA PAY DIRT. PHELPS DODGE ANNOUNCES PIT EXPANSION THAT WILL CARRY AJO MINE THROUGH 1980S. AUGUST 1979, P. 30.

  • Deposit

    PHELPS DODGE IS CONSTRUCTING MOLY PLANT AT AJO. APRIL 1980, P. 22.

  • Deposit

    PHELPS DODGE BRINGING COPPER MINE, MILL AT AJO BACK ON LINE. FEBRUARY 1983, FRONT COVER AND P. 5A.

  • Deposit

    ARIZONA PAY DIRT (SUPPLEMENT). AJO, IN PHELPS DODGE--A COPPER CENTENNIAL, 1881-1981. SUMMER 1981, PP. 64-68, 70-71, 90-91, AND 180-181.

  • Deposit

    PHELPS DODGE CORP. 1979 ANNUAL REPORT. PP. 6-7.

  • Deposit

    1981 ANNUAL REPORT. P. 5.

  • Deposit

    PHELPS DODGE TODAY (CORP. QUARTERLY PUB.). AJO'S NEW "MOLY" PLANT GOES INTO PRODUCTION. MARCH 1981, FRONT COVER AND P. 2.

  • Deposit

    AJO'S NEW WASTE DUMP SYSTEM AND THE D-10 DOZER. SEPTEMBER 1981, P. 8.

  • Deposit

    SW PAY DIRT, 8-90, P.7A.

  • Deposit

    PHELPS DODGE CORP 1994 10-K, P.14.

  • Deposit

    New Corenelia Copper Co. 1911-30 Annual reports; Phelps Dodge 1971-85 SEC Form 10K; USBM Minerals Yearbooks 1911-85; PCIA 1979-85

  • Deposit

    Cox and others (2006), Dixon (1966), Gilluly (1946), Long (1995), McDowell (1971), Niemuth (1994), Trischka (1938), Wilkinson and others (1999)

  • Deposit

    Dixon D W 1966 - Geology of the New Cornelia Mine, Ajo, Arizona: in Titley S R, Hicks C L 1966 Geology of the Porphyry Copper Deposits, Southwestern North America University of Arizona Press, Tucson pp 123-132

    Hagstrum J T, Cox D P, Miller R J 1987 - Structural reinterpretation of the Ajo mining district, Pima County, Arizona, based on paleomagnetic and geochronologic studies: in Econ. Geol. v82 pp 1348-1361

General comments

Subject category Comment text
Deposit The Copper Concentrate Transportation Cost Was Updated To Jan. 1987 Dollars For The Economic Time Diagrams Included In The Update Report Backup. Property Update July 1987.
Deposit Associated Minerals: albite, alunite, anhydrite/gypsum, biotite, barite, bornite, brochantite, carbonate, chalcocite, chalcopyrite, chlorite, chrysocolla, covellite, cuprite, epidote, gold, hematite/specularite, ilmenite, jarosite, magnetite, malachite, molybdenite, pyrite, sericite, shattuckite, sphalerite, tetrahedrite/tennantite
Deposit Associated Rocks: andesite dike, andesite porphyry dike, quartz diorite, quartz monzonite, quartz monzonite porphyry, pegmatite, rhyolite;gneiss;andesite flow, andesite breccia, fanglomerate, tuff
Deposit Mineralization Is Disseminations & Veinlets. Ore Body Is Well Shattered. Iron Minerals Are Associated With Copper Mineralization. Molybdenite Is Widely Scattered In The Ore Body.

Reporter information

Type Date Name Affiliation Comment
Updater 03-NOV-09 Anderson, Claire U.S. Geological Survey
Reporter 02-OCT-96 Rcs/Lmo U.S. Bureau of Mines
Reporter 01-MAR-83 Peterson, Jocelyn U.S. Geological Survey
Updater 01-OCT-81 Gest, Don E. Arizona Bureau of Geology and Mineral Technology
Updater 01-OCT-79 Johnson, Kris H. (Creasey, S.C.) U.S. Geological Survey
Updater 01-MAY-75 Cox, Dennis P. U.S. Geological Survey

Beyond USGS

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

Current status (per MSHA)

StatusAbandoned since 03/17/2004
MSHA mine ID0200156
Mine name (MSHA)FMI Ajo Operations
Current operatorFreeport McMoRan Copper & Gold
Current controller (parent)Freeport-McMoRan Inc
Mine typeSurface (Metal / non-metal)

MSHA cross-reference per the original MRDS record. Mine status and operator reflect MSHA's last published Mines export (February 2025); MSHA's public bulk feed has been unavailable since, so this may be out of date. See the Mine Data Retrieval System for current status.

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

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.