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Minnamax Cu-Ni Prospect

Prospect in St. Louis county in Minnesota, United States with commodities Copper, Nickel, Palladium, Platinum, Ruthenium, Osmium, Iridium, Rhodium, Titanium, Cobalt
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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. Ownership information
  19. Reserves and resources
  20. Workings at the site
  21. Links to other databases
  22. Bibliographic references
  23. General comments
  24. Reporter information

Geologic information

Identification information

Deposit ID 10039042
MRDS ID M046566
Record type Site
Current site name Minnamax Cu-Ni Prospect
Alternate or previous names Babbitt Deposit, Amax Underground Mine, Mesaba Project

Geographic coordinates

Geographic coordinates: -91.88323, 47.63166 (WGS84)

Site location context

Political divisions (FIPS codes)

St. Louis(county)

Minnesota(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Babbitt(quadrangle 1:24,000 scale)

Ely(quadrangle 1:100,000 scale)

Two Harbors(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Rainy Headwaters(hydrologic unit)

Rainy(hydrologic accounting unit)

Rainy(hydrologic subregion)

Souris-Red-Rainy(hydrologic region)

Federal lands

Superior 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 Minnesota St. Louis

Public Land Survey System information

Meridian Township Range Section Fraction State
4th Principal 060N}060N 012W}013W 29,30,31,32}36 Minnesota

Comments on the location information

  • Location taken from 1:250,000 scale map. T60N R12W; 5 MI SOUTH-SOUTHEAST OF BABBITT, 64 MI NORTH OF DULUTH

Commodities

Commodity Importance
Copper Primary
Nickel Critical Primary
Palladium Critical Primary
Platinum Critical Primary
Ruthenium Critical Secondary
Osmium Secondary
Iridium Critical Secondary
Rhodium Critical Secondary
Titanium Critical Secondary
Cobalt Critical Secondary

Comments on the commodity information

  • PGE MINERALS HAVE BEEN IDENTIFIED AT BABBITT (MINNIMAX). PGE MINERALIZATION IS KNOWN TO OCCUR ONLY ALONG THE WESTERN CONTACT OF THE 1.1 GA DULUTH COMPLEX. PASTERIS (1984, 1985) RECOGNIZED FIVE VARIETIES OF OXIDES IN THE BABBITT AND SPRUCE ROAD DEPOSITS: 1) SPINEL AND ILMENITE RODS IN PLAGIOCLASE; 2) INDIVIDUAL ILMENITE GRAINS; 3) INDIVIDUAL MAGNETITE GRAINS; 4) GRANULAR (COMPOSITE?) ILMENITE-MAGNETITE; AND 5) LAMELLAR ILMENITE IN MAGNETITE.
  • FOUR TIMES MORE PGES HERE THAN AT DUNKA ROAD. FIVE OF SEVEN DRILL HOLES CONTAIN ELEVATED PT+PD. SEVERSON (1991) AND SEVERSON AND BARNES (1991) CONTAIN NUMEROUS PGE DATA AND DISCUSSIONS OF PGE MINERALIZATION. SEE ALSO MORTON AND HAUCK (1989) NO PGE MINERALS HAVE BEEN IDENTIFIED IN LOCAL BOY AREA IN SPITE OF ANOMALOUS PGE, EXCEPT FOR A REPORT OF SPERRYLITE INCLUSIONS IN MAUCHERITE. PGE ARE ENRICHED IN SAMPLES WITH HIGHER CU/S RATIOS. IN ADDITION TO THE TYPICAL CU-NI MINERALS, ALSO PRESENT IN THE LOCAL BOY AREA ARE HIGHER AMOUNTS OF MAUCHERITE, SPHALERITE, BORNITE, TALNAKITE, MACKINAWITE, ZINCIAN HERCYNITE, AND NATIVE SILVER.
  • CU:NI=4.8:1. MOST ORES 2-3% SILFIDE, LOCALLY MASSIVE NEAR BASE. ONE CORE SAMPLE CONTAINS 14 PPM PT+PD OVER 4 FT. EIGHT PULP SAMPLES FROM VARIOUS ROCK TYPES CONTAINED A MAX. OF 12.52 PPM PD, 8.3 PPM PT, 25 PPB OS, 5.19 PPB IR, 30 PPB RU, 18.3 PPB RH. AU AND AG RAN AS HIGH AS 10.9 PPM AND 34 PPM, RESPECTIVELY, IN LOCAL BOY AREA. WEIGHTED AVERAGE OF COMBINED PT AND PD=378 PPB, OF AG=3.8 PPM, OF CU=0.98%, OF NI=0.22%. MEDIAN PT+PD=200 PPB. WHOLE ROCK CONCENTRATIONS FROM ORE ZONE ROCKS RAN 6.6 PPB OS, 6 PPB IR, 15.3 PPB RU, 15.5 PPB RH, 333 PPB PT, 1113 PPB PD, 147 PPB AU. REFERENCES: SEVERSON, 1991; SEVERSON AND BARNES, 1991; MORTON AND HAUCK, 1989, 1987; WEIBLEN, 1989. SEE MORTON AND HAUCK (1987) FOR AN EXTENSIVE DISCUSSION OF THE PGE MINERALIZATION IN THE MINNIMAX DEPOSIT AND FOR FURTHER ANALYTICAL DATA.
  • ALONG THE WESTERN MARGIN OF THE DULUTH COMPLEX, THE CU-NI SULFIDE RESOURCES ARE ESTIMATED AT 4.4 BILLION TONS OF 0.66 PERCENT CU WITH A CU:NI RATIO OF 3.3:1 (HAUCK AND OTHERS, 1997). PROVEN RESOURCES OF 248 MILLION TONNES AT O.4% CU, 0.17% NI IN 1981. SEVERSON AND BARNES (1991) PROVIDE GEOLOGIC RESOURCE ESTIMATES FOR THE LOCAL BOY AREA USING SEVERAL CU CUTOFF GRADE. 1991 ESTIMATES FROM SEVERSON AND BARNES, 1991; MORTON AND HAUCK, 1987, CITING OTHER PUBLICATION; LISTERUD AND MEINEKE, 1977

Materials information

Materials Type of material
Bornite Ore
Bravoite Ore
Chalcocite Ore
Chalcopyrite Ore
Copper Ore
Covellite Ore
Cubanite Ore
Digenite Ore
Galena Ore
Magnetite Ore
Pentlandite Ore
Pyrite Ore
Pyrrhotite Ore
Silver Ore
Sphalerite Ore
Tenorite Ore
Apatite Gangue
Biotite Gangue
Graphite Gangue
Olivine Gangue
Plagioclase Gangue
Ilmenite Unknown

Alteration

  • (Local) Pyroxene And Plagioclase Have Been Replaced By Amphiboles, Biotite, Chlorite, And Carbonate In Pge Rich Zone. Local Uralitization And Serpentinization

Analytical data

Result CU:NI=4.8:1. MOST ORES 2-3% SILFIDE, LOCALLY MASSIVE NEAR BASE. ONE CORE SAMPLE CONTAINS 14 PPM PT+PD OVER 4 FT. EIGHT PULP SAMPLES FROM VARIOUS ROCK TYPES CONTAINED A MAX. OF 12.52 PPM PD, 8.3 PPM PT, 25 PPB OS, 5.19 PPB IR, 30 PPB RU, 18.3 PPB RH. AU AND AG RAN AS HIGH AS 10.9 PPM AND 34 PPM, RESPECTIVELY, IN LOCAL BOY AREA. WEIGHTED AVERAGE OF COMBINED PT AND PD=378 PPB, OF AG=3.8 PPM, OF CU=0.98%, OF NI=0.22%. MEDIAN PT+PD=200 PPB. WHOLE ROCK CONCENTRATIONS FROM ORE ZONE ROCKS RAN 6.6 PPB OS, 6 PPB IR, 15.3 PPB RU, 15.5 PPB RH, 333 PPB PT, 1113 PPB PD, 147 PPB AU

Mineral occurrence model information

Model code 9
USGS model code 5a
Deposit model name Duluth Cu-Ni-PGE

Host and associated rocks

  • Host or associated Associated
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Argillite
    Rock unit name Virginia Formation
    Stratigraphic age (youngest) Paleoproterozoic
  • Host or associated Host
    Rock type Plutonic Rock > Mafic Intrusive Rock > Gabbro > Troctolite
    Rock unit name Partridge River Intrusion
    Stratigraphic age (youngest) Mesoproterozoic

Economic information

Geologic structures

Type of structure Local
Structure description Several Ne-Trending Normal Faults Parallel The Midcontinent Rift System Near The Margin. These Faults Formed During The Opening Of The Rift And Controlled Emplacement Of The Troctolitic And Late Intrusions.
Type of structure Local
Structure description In the Babbitt Area, The Grano Fault, A North-Trending Scissors Fault, Is In The Zone Separating The Partridge River And The South Kawishiwi Intrusions. Pre- To Syn-Complex Sub-Horizontal Folds Are Present In The Footwall Virginia Formation. Structural Contours On The Top Of The Biwabik Iron-Formation And At The Base Of The Duluth Complex Define Anticlinal And Synclinal Structures In The Bathtub And Local Boy

Ore body information

  • General form DISSEMINATED, MASSIVE, VEINLETS, SULFIDE-SILICATE INTERGROWTHS
    Strike N45E
    Dip 17SE
    Thickness 100M
    Length 6000M
    Width 115M
    Depth to top 430M
    Depth to bottom 532M

Controls for ore emplacement

  • Sulfides Segregated In Basal Troctolites Sub-Parallel To Lower Contacts
  • Faults And Folds Were Responsible For Localizing Sulfide Mineralization As Well As For Providing Conduits For Later Syn- To Post-Magmatic Hydrothermal Fluids. For Example, Structurally Controlled Massive Sulfides Of The Local Boy Are Are Associated With The Local Boy Anticline. Both Primary/Magmatic And Secondary/Hydrothermal Processes Appear To Have Been Factors In Controlling Pge Distribution In The Local Boy Area.

Comments on the geologic information

  • THE DULUTH COMPLEX IS A LARGE, COMPOSITE THOLEIITIC MAFIC INTRUSION THAT WAS EMPLACED INTO COMAGMATIC FLOOD BASALTS ALONG A PORTION OF THE MIDDLE PROTEROZOIC (1.1 GA, KEWEENAWAN) MIDCONTINENT RIFT SYSTEM.
  • INTRUSION CONTAINS 7 SUBHORIZONTAL TROCTOLITIC UNITS, HORNFELSED INCLUSIONS, AND A LATE PEGMATITIC PHASE. PROCESS OF ORE FORMATION INVOLVED DEVOLATILIZATION AND PARTIAL MELTING OF COUNTRY ROCKS, WHICH PROVIDED SOURCE OF SULFUR. ORES ARE ISOTOPICALLY INHOMOGENEOUS. METASEDIMENTARY XENOLITHS ARE COMMON AROUND THE ORE. SULFIDES ORIGINATED AS INTERCUMULATE IN LITHIFYING TROCTOLITE WHEN SULFUR WAS INTRODUCED INTO LIQUID FRACTION CREATING IMMISCIBLE SULFIDE AND SILICATE LIQUIDS. HIGHER DENSITY OF SULFIDE AND BASAL INTRODUCTION OF SULFUR CREATED BASAL LOCALIZATION. VARIATION IN SULFUR SOURCE, PATHWAYS, AND FAULTING CREATED LOCAL VARIATION AND HIGHER HORIZONS. GRAPHITE IN THE DULUTH COMPLEX MAY HAVE DEVELOPED BY REACTION OF THE HYDROCARBONS FUMED FROM SLATE IN THE UNDERLYING METASEDIMENTS WITH THE CRYSTALLIZING TROCTOLITIC MAGMA.
  • FAULTS AND FOLDS WERE RESPONSIBLE FOR LOCALIZING SULFIDE MINERALIZATION AS WELL AS FOR PROVIDING CONDUITS FOR LATER SYN- TO POST-MAGMATIC HYDROTHERMAL FLUIDS. FOR EXAMPLE, STRUCTURALLY CONTROLLED MASSIVE SULFIDES OF THE LOCAL BOY ARE ARE ASSOCIATED WITH THE LOCAL BOY ANTICLINE. BOTH PRIMARY/MAGMATIC AND SECONDARY/HYDROTHERMAL PROCESSES APPEAR TO HAVE BEEN FACTORS IN CONTROLLING PGE DISTRIBUTION IN THE LOCAL BOY AREA. SULFIDES SEGREGATED IN BASAL TROCTOLITES SUB-PARALLEL TO LOWER CONTACTS. FAULTING RELATED TO RIFT ORIGIN OF DULUTH COMPLEX. SEVERAL NE-TRENDING NORMAL FAULTS PARALLEL THE MIDCONTINENT RIFT SYSTEM NEAR THE MARGIN. THESE FAULTS FORMED DURING THE OPENING OF THE RIFT AND CONTROLLED EMPLACEMENT OF THE TROCTOLITIC AND LATE INTRUSIONS.
  • IN THE BABBITT AREA, THE GRANO FAULT, A NORTH-TRENDING SCISSORS FAULT, IS IN THE ZONE SEPARATING THE PARTRIDGE RIVER AND THE SOUTH KAWISHIWI INTRUSIONS. PRE- TO SYN-COMPLEX SUB-HORIZONTAL FOLDS ARE PRESENT IN THE FOOTWALL VIRGINIA FORMATION. STRUCTURAL CONTOURS ON THE TOP OF THE BIWABIK IRON-FORMATION AND AT THE BASE OF THE DULUTH COMPLEX DEFINE ANTICLINAL AND SYNCLINAL STRUCTURES IN THE BATHTUB AND LOCAL BOY ORE ZONES. LOCAL BOY ANTICLINE AND BATHTUB SYNCLINE ARE PROMINENT LOCAL STRUCTURES. PYROXENE AND PLAGIOCLASE HAVE BEEN REPLACED BY AMPHIBOLES, BIOTITE, CHLORITE, AND CARBONATE IN PGE RICH ZONE. LOCAL URALITIZATION AND SERPENTINIZATION IMPORTANT.

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic
Deposit size Medium
Significant Yes
Discovery year 1957
Discoverer Bear Creek Mining Co.

Mining district

District name Western Margin Duluth Complex

Mineral rights holdings

Type of mineral rights State Lease
Type of mineral rights Private Lease
Type of mineral rights Federal Lease

Ownership information

  • Type Operator
    Owner Rhude And Fryberger, Inc.
    Home office Hibbing, Mn.
    First year 1991
  • Type Operator
    Owner Amax Exploration, Inc.
  • Type Operator
    Owner Arimetco International, Inc
    First year 1995
  • Type Owner
    Owner Longyear Mesaba Co.
    First year 1995

Reserves and resources

  • Type In-situ
    Estimate year 1991
    Total resources 21900mt ore
    Commodity Subtype Grade units Group Importance Year
    Copper Cu 1.08 wt-pct Copper Major 1991
    Nickel Ni 0.2 wt-pct Nickel Major 1991
  • Type In-situ
    Estimate year 1981
    Total resources 190mt ore
    Commodity Subtype Grade units Group Importance Year
    Copper Cu 0.54 wt-pct Copper Major 1981
    Nickel Ni 0.13 wt-pct Nickel Major 1981
  • Type In-situ
    Estimate year 1977
    Total resources 362mt ore
    Commodity Subtype Grade units Group Importance Year
    Copper Cu 0.5 wt-pct Copper Major 1977
    Nickel Ni 0.3 wt-pct Nickel Major 1977

Comments on the reserve resource information

  • ALONG THE WESTERN MARGIN OF THE DULUTH COMPLEX, THE CU-NI SULFIDE RESOURCES ARE ESTIMATED AT 4.4 BILLION TONS OF 0.66 PERCENT CU WITH A CU:NI RATIO OF 3.3:1 (HAUCK AND OTHERS, 1997). PROVEN RESOURCES OF 248 MILLION TONNES AT O.4% CU, 0.17% NI IN 1981. SEVERSON AND BARNES (1991) PROVIDE GEOLOGIC RESOURCE ESTIMATES FOR THE LOCAL BOY AREA USING SEVERAL CU CUTOFF GRADE. 1991 ESTIMATES FROM SEVERSON AND BARNES, 1991; MORTON AND HAUCK, 1987, CITING OTHER PUBLICATION; LISTERUD AND MEINEKE, 1977.
  • 1974 RESOURCE GRADE ESTIMATES: 100,000 MT AT 0.8% CU + NI IS PROBABLE ESTIMATE FROM AMAX: 220,000 MT AT 0.8 CU + NI IS POSSIBLE ESTIMATE REPRESENTS THE MEAN OF SEVERAL CALCULATIONS BASED ON DRILL-CORE DATA.

Workings at the site

  • Type of workings Underground
    Length 6000M
    Overall depth 490M

Comments on the workings information

  • SHAFT SUNK IN 1976. DIMENSIONS LISTED ARE ESTIMATES ONLY AS THERE HAS BEEN LITTLE DEVELOPMENT THUS FAR.

Comments on development

  • MINNIMAX WAS DISCOVERED IN 1957 BY BEAR CREEK MINING. DISCOVERY WAS A RESULT OF GEOLOGIC MAPPING, FOLLOWED BY GEOPHYSICAL AND GEOCHEMICAL SURVEYS. RESULTS CONTROLLED BY EXTENSIVE DIAMOND DRILLING. MINERALIZED ROCKS WERE FIRST DISCOVERED NEAR ELY IN 1948 BY CHILDERS AND WHITESIDES. AMAX DROPPED THEIR LEASES IN THE MID 1980'S ; ECON.COM: ENVIRONMENTAL CONSIDERATIONS ARE PRESENT, BUT BABBITT AREA IS MINING ORIENTED ALREADY.

Reference information

Comments on the other database information

  • RECORD W018673 HAS BEEN MERGED AND DELETED. RECORD W062170 (BABBITT) WAS ALSO MERGED AND DELETED.

Bibliographic references

General comments

Subject category Comment text
Deposit ONE OF LARGER DEPOSITS IN DULUTH COMPLEX. DEPOSIT IS SUBDIVIDED INTO 5 ORE ZONES INCLUDING LOCAL BOY, BATHTUB, TIGER BOY, UPDIP, AND SW EXTENSION AREAS. THE LOCAL BOY ORE ZONE IS A MASSIVE SULFIDE DEPOSITS WITH ASSOCIATED PGE-ENRICHED ZONES. THERE ARE TWO TYPES OF MINERALZATION, BASAL MINERALIZATION NEAR THE BASE OF THE TROCTOLITE AND CLOUD MINERALIZATION ABOAUT 500-600 FT ABOVE BASE OF COMPLEX. SULFIDES ARE LOCALLY MASSIVE NEAR BASE BUT MOST ORE IS INTERSTITIAL. LESS ORE IS INTERGROWN WITH SILICATES OR IS IN EXSOLUTIONS. SOME ORE IS PRESENT IN FOOTWALL ROCKS OF VIRGINIA FORMATION. PGE MAY BE PARTLY MAGAMTIC AND PARTLY HYDROTHERMAL IN ORIGIN. SULFIDES ARE DISSEMINATED, MASSIVE, OR IN VEINLETS, WITH SULFIDE-SILICATE INTERGROWTHS.
Deposit SEE MORTON AND HAUCK (1987) FOR AN EXTENSIVE DISCUSSION OF THE PGE MINERALIZATION IN THE MINNIMAX DEPOSIT AND FOR FURTHER ANALYTICAL DATA ; INFO.SRC : 1 PUB LIT; 2 UNPUB REPT
Deposit RECORD W018673 HAS BEEN MERGED AND DELETED.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-JAN-1961 Sutphin, D.M. (Cannon, W.F.) U.S. Geological Survey
Updater 01-MAR-1997 Sutphin, D.M. U.S. Geological Survey
Editor 01-MAY-1997 Mason, Jr., G.T. U.S. Geological Survey
Reporter 01-APR-1976 Page, Norman U.S. Geological Survey
Updater 01-JAN-1990 Peterson, J.A. U.S. Geological Survey
Editor 01-DEC-2003 Woodruff, Laurel G. U.S. Geological Survey Work done in Filemaker
Editor 28-FEB-2005 Woodruff, L.G. U.S. Geological Survey

Beyond USGS

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