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Crown/City Deep/Cons. Main Reef Mines

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

Geologic information

Identification information

Deposit ID 10079049
MRDS ID W027864
Record type Site
Current site name Crown/City Deep/Cons. Main Reef Mines

Geographic coordinates

Geographic coordinates: 28.01812, -26.22993 (WGS84)
Elevation 1646
Relative position ADJOINS CITY OF JOHANNESBURG

Site location context

Political divisions (FIPS codes)

South Africa(country)

Africa(continent)

Land(continent)

Geographic areas

Country
South Africa

Comments on the location information

  • LOCATION GIVEN IS CROWN MINES SHAFT. CROWN, CITY DEEP AND CONS. MAIN REEF MINES WERE MERGED INTO ONE PRODUCER AT YEAR-END 1973 . THE THREE ARE ADJACENT PROPERTIES WITH CROWN IN THE CENTER. CITY DEEP IS SOUTHEAST OF CROWN; CONS. MAIN REEF IS NORTHWEST OF CROWN.

Commodities

Commodity Importance
Gold Primary
PGE Critical Secondary
Silver Secondary

Comments on the commodity information

  • SMALL QUANTITIES PT AND AG RECOVERED BUT UNIMPORTANT IN SOUTH AFRICA TERMS. PT IS AN IMPURITY IN GOLD AND IS RECOVERED AT THE RAND REFINERY AS A CONSEQUENCE OF THE PURIFICATION PROCESS.

Alteration

  • (Local) None

Analytical data

Result SEE PRODUCTION ENTRIES

Host and associated rocks

  • Host or associated Associated
    Rock type Volcanic Rock (Aphanitic)
    Rock unit name Ventersdorp System-Lava
    Rock description Ventersdorp System-Lavas
    Stratigraphic age (youngest) Neoproterozoic
    Stratigraphic age (youngest) Neoproterozoic
    Stratigraphic age (youngest) Neoproterozoic
    Stratigraphic age (youngest) Neoproterozoic
  • Host or associated Host
    Rock type Metamorphic Rock > Metasedimentary Rock > Quartzite
    Rock unit name Witwatersrand System (Upper Division)-Quartzites, Shales, Grits, Conglomerates And Carbon Granules
    Rock description Witwatersrand System (Upper Division)-Quartzites, Shales, Grits, Conglomerates And Carbon Granules
  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Shale
  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Conglomerate
  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic)

Nearby scientific data

(1) 28.01812, -26.22993
ListMap

Economic information

Geologic structures

Type of structure Regional
Structure description Unique Continuity Of Gold-Bearing Horizons Over Extended Area, Though Well Marked By Faulting And Folding, And (Locally) Erosion And Redeposition Of Overlying Sediments.
Type of structure Local
Structure description Steep Dips Near Surface, Decreasing To Less Than 15 Degrees At Depth Of 3,000 Meters. Folds And Faults Locally. Intrusive Dikes Penetrate And Dilute Minable Ore Horizons.

Ore body information

  • General form TABULAR/BLANKET
    Strike E - W
    Dip 60 DEG. S
    Thickness 2.5M
    Depth to top 2816.5M
    Depth to bottom 2819M

Controls for ore emplacement

  • Gentle Uplift Of Continental Mass; Erosion; Peneplanation; Folding; Faulting; Volcanicity; Dike Injection And Build-Up Of Younger Sediments.

Economic information about the deposit and operations

Development status Producer
Commodity type Metallic
Deposit size Large
Significant No
Discovery year 1887
Year of first production 1887

Mining district

District name Central Rand Of The Witwatersrand Goldfields

Land status

Ownership category Private

Ownership information

  • Type Operator
    Owner Rand Mines Properties Ltd.
  • Type Owner
    Owner Barlow Rand Ltd.

Production statistics

  • Year 1977
    Period 1974 - 1977
    Material ORE
    Accuracy Accurate
    Description Cp_Grade: ^Wgtd. Ave. Grade: 0.106 Toz Au Met. Ton Of Ore Milled.
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Ore Gold Gold 0g/mt
  • Year 1977
    Material ORE
    Accuracy Accurate
    Description Ap_Grade: ^0.104 Toz Au Met Ton Of Ore Milled
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Ore Gold Gold 0g/mt

Comments on the production information

  • PRODUCTION FROM CROWN, CITY DEEP AND CONS. MAIN REEF MINES REPORTED AS ONE TOTAL ANNUALLY SINCE 1974 . EARLIER CUMULATIVE TOTALS, BY MINE, ARE: CROWN ( 1897 - 1973 ) - 161,035,000 MET. TONS ORE MILLED (AVE. GR.: 0.281 TR. OZ/TON) AND 45.2 MILLION TROY OUNCES GOLD; CITY DEEP ( 1910 - 1973 ) 66,149,000 MET TONS ORE MILLED (AVE. GR.: 0.276 TR. OZ/TON) AND 18.3 MILLION TROY OUNCES GOLD; AND CONS. MAIN REEF ( 1898 - 1973 ) - 68,092,000 MET. TONS ORE MILLED (AVE. GR.: 0.215 TR. OZ/TON) AND 14.7 MILLION TROY OUNCES GOLD.

Comments on the reserve resource information

  • RESERVES NO LONGER PUBLISHED (SEE ECONOMIC COMMENTS)

Workings at the site

  • Type of workings Underground
    Overall depth 2819M

Comments on the workings information

  • MINING METHOD HAS ALWAYS BEEN LABOR-INTENSIVE "SCATTER MINING" WITH TIMBER AND (RECENTLY) CONCRETE GROUTED CRIB STOPE SUPPORTS. SLUSHING AND ORE HAULAGE MECHANIZED. WATER ENCROACHMENT, EXCESSIVE DEPTHS AND LOW GOLD VALUES HAVE COMBINED TO CREATE PHASE-DOWN OF MINING IN ALL THREE PROPERTIES. (SEE, ALSO, ECONOMIC COMMENTS).

Comments on development

  • CROWN/CITY DEEP/CONS. MAIN REEF ARE THREE OF SOUTH AFRICA'S OLDEST GOLD MINES; EACH NOW IN FINAL PRODUCTION PHASE ; MILL.CAP: 1.0 MIL. MET. T/YR. ; ECON.COM: CITY DEEP: UNDERGROUND MINING OPERATIONS SUSPENDED NOVEMBER 1976 . CONS MAIN REEF: UNDERGROUND MINING OPERATIONS SUSPENDED AUGUST 1975 , CLEAN-UP AT EACH CONTINUES AND CROWN MINES NEARING END OF ITS PRODUCTION LIFE.

Reference information

Bibliographic references

  • Deposit

    MINERAL RESOURCES OF SOUTH-CENTRAL AFRICA; PELLETIER, R.A.; 1964

  • Deposit

    MINERAL RESOURCES OF THE REPUBLIC OF SOUTH AFRICA, FIFTH EDITION, HANDBOOK 7 ; 1976

  • Deposit

    BARLOW RAND LIMITED ANNUAL REPORT; 1975

  • Deposit

    CHAMBER OF MINES OF SOUTH AFRICA, 1951, MINING SURVEY: CHAMBER OF MINES OF SOUTH AFRICA, V. 3, NO. 4, SEPTEMBER 1951.

  • Production

    ANALYSIS OF WORKING RESULTS; CHAMBER OF MINES OF SOUTH AFRICA; ANNUAL REPORTS 1976 , 1977

General comments

Subject category Comment text
Deposit MAX THICKNESS REFERS TO MAIN REEF LEADER HORIZON IN EASTERN PORTION OF CROWN MINES. THIS HORIZON (VEIN) THINS TO 0.3 METER IN CONS. MAIN REEF MINE. ALSO IMPORTANT IS THE MAIN REEF HORIZON AT AVERAGE THICKNESS OF 1.5 METERS. DEPTH TO BOTTOM IS APPROX. MAXIMUM MINING DEPTH IN CROWN MINES.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-FEB-1978 Sweetwood, Charles W. Department of State

Beyond USGS

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

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