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Grootboom Chrome Mine

Producer in South Africa with commodities Chromium, PGE, Iron, Silica
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Commodities
  6. Materials information
  7. Mineral occurrence model information
  8. Host and associated rocks
  9. Nearby scientific data
  10. Ore body information
  11. Economic information about the deposit and operations
  12. Mining district
  13. Land status
  14. Ownership information
  15. Reserves and resources
  16. Workings at the site
  17. Links to other databases
  18. Bibliographic references
  19. General comments
  20. Reporter information

Geologic information

Identification information

Deposit ID 10107358
MRDS ID W028413
Record type Site
Current site name Grootboom Chrome Mine

Geographic coordinates

Geographic coordinates: 30.171, -24.7838 (WGS84)
Elevation 762
Location accuracy 100(meters)
Relative position 5 KILOMETERS SOUTHWEST OF STEELPOORT

Site location context

Political divisions (FIPS codes)

South Africa(country)

Africa(continent)

Land(continent)

Geographic areas

Country
South Africa

Commodities

Commodity Importance
Chromium Critical Primary
PGE Critical Tertiary
Iron Tertiary
Silica Tertiary

Materials information

Materials Type of material
Chromite Ore
Anorthosite Gangue
Chalcopyrite Gangue
Pentlandite Gangue
Pyrrhotite Gangue

Analytical data

Result LUMP ORE: SIZE - 102 MM PLUS 25 MM
Result CR2O3 39 - 40 %, SIO2 9 - 8 %
Result CR:FE 1.5:1 CONCENTRATES: SIZE: - 9 MESH
Result CR2O3 44 - 45 %. SIO2 2.7 %
Result SAND: CR2O3 44.5 - 45.5 %, SIO2 1.5 %, CR:FE 1.5:1
Result SPECIAL REFRACTORY ORE: CR2O3 45 - 46 %, SIO2 1 % MAX., CR:FE 1.5:1

Mineral occurrence model information

Model code 2
USGS model code 2a
Deposit model name Bushveld Cr

Host and associated rocks

  • Host or associated Associated
    Rock type Plutonic Rock > Ultramafic Intrusive Rock
    Rock unit name Bushveld Igneous Complex
    Stratigraphic age (youngest) Paleoproterozoic
  • Host or associated Host
    Rock type Plutonic Rock > Ultramafic Intrusive Rock > Pyroxenite
    Stratigraphic age (youngest) Pliocene

Nearby scientific data

(1) 30.171, -24.7838
ListMap

Economic information

Ore body information

  • Name Bushveld Complex Upper, Middle and Lower seams
    General form Tabular/Blanket
    Strike N - S
    Dip 15 DEG W
    Thickness 1.2M
    Depth to top 250M

Comments on the geologic information

  • The area's upper, middle and lower chrome groups (underlying the Merensky Reef) are extraordinarily uniform as to composition and thickness. This deposit lies south of (and near to) a major fault striking through this region -- the Steelpoort Fault -- but has not been notably affected by it. Faults and folds locally (as, say, disturbances complementary to the Steelpoort Fault) are of minor importance only. Seam undulations, however, are common and thus present localized changes in the dip.
  • Inward-dipping cone-like structure; folding and faulting (including low-angle thrusting) exists, but are of minor importance; erosion, peneplanation and build-up of younger sediments are basic criteria regionally.
  • The suite of igneous and volcanic rocks comprising the Bushveld Igneous Complex is believed to have derived from a common magma. Selective differentiation followed, from ultrabasics to acid rocks with (selective) concentrations of ore minerals and metals.
  • Surface and near-surface alterations of feldspathic materials only.
  • Igneous complex have been emplaced as sheet-like masses into the Pretoria Series volcanics (Transvaal system), and in some cases into one another, dipping inward toward the center giving a cone-like structure to the complex as a whole.
  • The sulfides listed in the Materials section as "gangue" are only gangue if only chromite recovery is assumed. These sulfides are probably the source of PGE mineralization. Tailings from this mine have been evaluated for PGE potential to reprocess.

Economic information about the deposit and operations

Operation type Surface-Underground
Development status Producer
Significant No
Year of first production 1957

Mining district

District name Eastern (Groothoek-Mecklenburg) Belt; Bushveld Igneous Complex

Land status

Ownership category Private

Ownership information

  • Type Operator
    Owner Lavino South Africa (Pty) Ltd
    First year 1950
    Last year 1980
  • Type Owner
    Owner International Minerals And Chemical Corp. Ltd.
    First year 1980
    Last year 1988
  • Type Owner
    Owner Anglovaal Limited
    First year 1988
    Last year 1994
  • Type Owner
    Owner Samancor
    Year 2009
    First year 1994

Reserves and resources

  • Type In-situ
    Estimate year 1975
    Total resources 15000000mt
    Commodity Subtype Grade units Group Importance Year
    Chromium Cr2O3 35 wt-pct Chromium Primary 1975

Comments on the reserve resource information

  • INDICATED RESERVES TO A VERTICAL DEPTH OF 250 METERS.

Workings at the site

  • Type of workings Surface/Underground
    Overall depth 250M

Comments on the workings information

  • Mining is by open pit and development drifts and inclines in ore to create modified room and piller method. Longhole drilling and modified longwall mining are used in areas of uniform seam thickness and dip. Broken ore is moved downward into ore passes by slusher to footwall drives below the mining seam and rail hauled to main haulage incline shafts. Surface facilities consist of hand sorting, screens, ball mills, vibratory tables and washing. Output consists of hand cobbed lump ore and treated fines as concentrates.

Comments on development

  • MILL.CAP: 0.3 MIL. MT/YR. ; ECON.COM: SECOND LARGEST CHROMITE (AND SAND) PRODUCER IN SOUTH AFRICA. PRODUCTION AND MARKETING EXPORT ORIENTED. CLOSE PROXIMITY TO RAIL ( 5 KILOMETERS ) AND LONG-TERM CONTRACTS THROUGH U.S. PARENT (IMC CORP.) ARE MAJOR ECONOMIC CONSIDERATIONS.

Reference information

Bibliographic references

  • Deposit

    Mineral Resources Of The Republic Of South Africa, Fifth Edition, Handbook 7, Geological Survey, Department Of Mines; 1976.

  • Analytical Data

    Src.Ref: Ferrous And Nonferrous Mines And Works In South Africa; Department Of Mines, Minerals Bureau; Directory No. 3/79; 1979

  • Deposit

    Marketing Directory, No. 2 , Ferrous And Nonferrous Metals And Minerals In South Africa; Minerals Bureau, Department Of Mines; 1977 .

  • Deposit

    Operating Mines In The Republic Of South Africa; Minerals Bureau, Department Of Mines; Directory No. 1/79 ; 1979 .

  • Deposit

    Deyoung And Others, 1984, International Strategic Minerals Inventory Summary Report-- Chromium: U.S. Geological Survey Circular 930-B, 41 P.

  • Deposit

    "Chromium And Ferrochromium In South Africa"; Saunders And Taylor, Stock And Share Brokers; Johannesburg; November 1975 .

  • Deposit

    "The Chromite Deposits Of The Bushveld Igneous Complex", Geological Survey, Department Of Mines; Kupferburger, W., And Lombaard B. V. 1937

General comments

Subject category Comment text
Deposit Max. thickness refers to in situ width of the "main" (Steelpoort) chromite seam (sometimes referred to as the "middle seam") in the area's "lower chrome group". Two additional seams are minable, but not presently worked; the "upper seam" ( 0.5 meter thick ) and the "lower seam" ( 0.5 meter thick ). Depth to top is the range from sub-outcrop of "main seam" to current vertical max. mining depth. Depth to bottom (i.e. maximum depth of minable ore) not known. Strike and dip given are averages in current mining area, but otherwise highly variable throughout leased area.
Deposit Information merged from record numbers (OldMRDS) W028892 ; W030791 ; W032264

Reporter information

Type Date Name Affiliation Comment
Reporter 01-AUG-79 Sweetwood, Charles W. Department of State
Reporter 01-JUL-82 McCarter, Lorna D. Department of State
Updater 19-JUL-10 Causey, J. Douglas U.S. Geological Survey

Beyond USGS

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

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