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Crown Mine (Lace Mine), Kroonstad, Fezile Dabi District, Free State, South Africai
Regional Level Types
Crown Mine (Lace Mine)Mine
Kroonstad- not defined -
Fezile Dabi DistrictDistrict
Free StateProvince
South AfricaCountry

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Latitude & Longitude (WGS84): 27° 27' 2'' South , 27° 6' 50'' East
Latitude & Longitude (decimal): -27.45056,27.11389
GeoHash:G#: ke57bfz8z
Locality type:Mine
Köppen climate type:BSk : Cold semi-arid (steppe) climate


A small diamond mine in a kimberlite pipe, currently owned by DiamondCorp. The pipe forms part of a cluster of eleven intrusions, most of which have no economic diamond grades. It was discovered by De Beers in 1896 and considered uneconomic. It was then taken over by the Lace Diamond Mining Company, who mined it from 1902 to 1907. In 1908, it was sold to the Crown D.M. and E. Company, who worked it until 1910, and again from 1913 to 1931. De Beers subsequently re-acquired the property, but sold it again in the late 1990s. The current owner is presently considering to re-open the underground mine. Re-treatment of the dumps started in 2007.

The mine produced diamonds of high quality, but due to the high percentage of inferior < 1 ct stones, the overall value was low. The largest diamond ever recovered was an 86.5 ct stone in 1930.

Regions containing this locality

Witwatersrand Gold Fields, South Africa

Mining Region - 278 mineral species & varietal names listed

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List


4 valid minerals.

Detailed Mineral List:

Corundum
Formula: Al2O3
Reference: Mathias, M., Siebert, J.C., and Rickwood, P.C. (1970): Contributions to Mineralogy and Petrology 26, 75-123.
Diamond
Formula: C
Reference: Field, M., Stiefenhofer, J., Robey, J., and Kurszlaukis, S. (2008): Ore Geology Reviews 34, 33-75.
'Garnet Group'
Formula: X3Z2(SiO4)3
Reference: Field, M., Stiefenhofer, J., Robey, J., and Kurszlaukis, S. (2008): Ore Geology Reviews 34, 33-75.
Kyanite
Formula: Al2(SiO4)O
Reference: Field, M., Stiefenhofer, J., Robey, J., and Kurszlaukis, S. (2008): Ore Geology Reviews 34, 33-75.
Phlogopite
Formula: KMg3(AlSi3O10)(OH)2
Reference: Field, M., Stiefenhofer, J., Robey, J., and Kurszlaukis, S. (2008): Ore Geology Reviews 34, 33-75.

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
'Diamond'1.CB.10aC
Group 4 - Oxides and Hydroxides
'Corundum'4.CB.05Al2O3
Group 9 - Silicates
'Kyanite'9.AF.15Al2(SiO4)O
'Phlogopite'9.EC.20KMg3(AlSi3O10)(OH)2
Unclassified Minerals, Rocks, etc.
'Garnet Group'-X3Z2(SiO4)3

List of minerals arranged by Dana 8th Edition classification

Group 1 - NATIVE ELEMENTS AND ALLOYS
Semi-metals and non-metals
Diamond1.3.6.1C
Group 4 - SIMPLE OXIDES
A2X3
Corundum4.3.1.1Al2O3
Group 52 - NESOSILICATES Insular SiO4 Groups and O,OH,F,H2O
Insular SiO4 Groups and O, OH, F, and H2O with cations in [4] and >[4] coordination
Kyanite52.2.2c.1Al2(SiO4)O
Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings
Sheets of 6-membered rings with 2:1 layers
Phlogopite71.2.2b.1KMg3(AlSi3O10)(OH)2
Unclassified Minerals, Rocks, etc.
'Garnet Group'-X3Z2(SiO4)3

List of minerals for each chemical element

HHydrogen
H PhlogopiteKMg3(AlSi3O10)(OH)2
CCarbon
C DiamondC
OOxygen
O CorundumAl2O3
O Garnet GroupX3Z2(SiO4)3
O KyaniteAl2(SiO4)O
O PhlogopiteKMg3(AlSi3O10)(OH)2
MgMagnesium
Mg PhlogopiteKMg3(AlSi3O10)(OH)2
AlAluminium
Al CorundumAl2O3
Al KyaniteAl2(SiO4)O
Al PhlogopiteKMg3(AlSi3O10)(OH)2
SiSilicon
Si Garnet GroupX3Z2(SiO4)3
Si KyaniteAl2(SiO4)O
Si PhlogopiteKMg3(AlSi3O10)(OH)2
KPotassium
K PhlogopiteKMg3(AlSi3O10)(OH)2

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org

Jurassic - Permian
145 - 298.9 Ma



ID: 3309804

Age: Phanerozoic (145 - 298.9 Ma)

Lithology: Sedimentary (karoo)

Reference: Thiéblemont, D. (ed.). New edition of the 1:10,000,000 geological map of Africa. CGMW-BRGM. [190]

Permian
251.902 - 298.9 Ma



ID: 2234951
Volksrust Formation of Ecca Group of Karoo Supergroup

Age: Phanerozoic (251.902 - 298.9 Ma)

Stratigraphic Name: Volksrust Formation

Description: Mudrock

Reference: Council for Geoscience. Geologic map of South Africa, 1:1M. National Science Councils of South Africa. [41]

Permian
251.902 - 298.9 Ma



ID: 3189153
Paleozoic sedimentary rocks

Age: Phanerozoic (251.902 - 298.9 Ma)

Stratigraphic Name: Karoo Supergroup

Comments: Karoo Basin

Lithology: Sedimentary rocks

Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. [154]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Merensky, H. (1909). Geological observations in the Lace Diamond mine, now known as Crown Diamond mine. Transactions of the Geological Society of South Africa, 12, 203-204.
Mathias, M., Siebert, J.C., and Rickwood, P.C. (1970): Some Aspects of the Mineralogy and Petrology of Ultramafic Xenoliths in Kimberlite. Contributions to Mineralogy and Petrology 26, 75-123.
Field, M., Stiefenhofer, J., Robey, J., and Kurszlaukis, S. (2008): Kimberlite-hosted diamond deposits of southern Africa: A review. Ore Geology Reviews 34, 33-75.


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