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Black Rock Mine, Black Rock, Kalahari manganese field, Northern Cape Province, South Africa

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Latitude & Longitude (WGS84): 27° 7' 59'' South , 22° 49' 59'' East
Latitude & Longitude (decimal): -27.13333,22.83333
GeoHash:G#: ke0jxsd8z
Locality type:Mine
Köppen climate type:BSh : Hot semi-arid (steppe) climate


A manganese property owned by Associated Manganese Mines of South Africa, Ltd.

Note: Sturmanite an approved IMA mineral is erroneously reported from this mine, whilst it is said to be the type locality there must have been faulty labelling as it has never been found since with the associated minerals as described in the original paper whereas at least 5 pockets at Wessels mine between 1978 - 1982 have yielded crystals of similar habit. No specimens have ever been recorded from this mine and it was closed many years before. It is widely believed Black Rock is an erroneous locality and Wessels is the true locality. This has been checked against several references from Cairncross et al and von Bezing (Debbie Woolf).

Regions containing this locality

Kalahari Desert, Africa

Desert - 258 mineral species & varietal names listed

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List


24 valid minerals. 1 (TL) - type locality of valid minerals. 1 (FRL) - first recorded locality of unapproved mineral/variety/etc. 1 erroneous literature entry.

Detailed Mineral List:

Aegirine
Formula: NaFe3+Si2O6
Description: Common in the Wessels-type ore
Reference: Von Bezing, K. L. et al. (1991): The Kalahari manganese field: An Update, Mineralogical Record: 22(4), pp 281.
Andradite
Formula: Ca3Fe3+2(SiO4)3
Reference: Von Bezing, K. L. et al. (1991) The Kalahari manganese field: An Update, Mineralogical Record 22(4) pp 281; Cairncross, B. and Dixon, R., (1995) Minerals of South Africa. The Geological Society of South Africa: pp 183.
'Apatite'
Habit: massive
Description: micromount specimens
Reference: South African Micromount Society, Kalahari Manganese Fields - KMF, by Dixon, R., and Bezing, L. Von., (1989) Locality datasheet ML 02
Banalsite
Formula: Na2BaAl4Si4O16
Habit: massive
Description: micromount specimens
Reference: South African Micromount Society, Kalahari Manganese Fields - KMF, by Dixon, R., and Bezing, L. Von., (1989) Locality datasheet ML 02
Baryte
Formula: BaSO4
Reference: Peacor, D. R., Dunn, P. J., & Duggan, M. (1983). Sturmanite, a ferric iron, boron analogue of ettringite. Canadian Mineralogist, 21, 705-709.
Bixbyite
Formula: Mn3+2O3
Reference: South African Micromount Society, Kalahari Manganese Fields - KMF, by Dixon, R., and Bezing, L. Von., (1989) Locality datasheet ML 02
Braunite
Formula: Mn2+Mn3+6(SiO4)O8
Reference: Minerals of South Africa
'Braunite-II' (FRL)
Formula: CaMn3+14(SiO4)O20
Reference: American Mineralogist (1967): 52, 20-30; Von Bezing, K. L. et al. (1991) The Kalahari manganese field: An Update, Mineralogical Record 22(4) pp 282; Cairncross, B. and Dixon, R., (1995) Minerals of South Africa. The Geological Society of South Africa: pp 190; Cairncross, B., and Beukes, N. J., (2013) The Kalahari Manganese Field, the adventure continues. Struik Nature Publishers, Cape Town, South Africa, pp 156.
Calcite
Formula: CaCO3
Description: Crystals very common up to cabinet size (SAMS datasheet ML 02).
Reference: South African Micromount Society, Kalahari Manganese Fields - KMF, by Dixon, R., and Bezing, L. Von., (1989) Locality datasheet ML 02;
Celestine
Formula: SrSO4
Reference: Jordi Fabre photo
Cryptomelane
Formula: K(Mn4+7Mn3+)O16
Reference: Minerals of South Africa
Cymrite
Formula: BaAl2Si2(O,OH)8 · H2O
Reference: Minerals of South Africa
Ettringite ?
Formula: Ca6Al2(SO4)3(OH)12 · 26H2O
Reference: Rob Lavinsky photo
Gaudefroyite
Formula: Ca4Mn3+2-3(BO3)3(CO3)(O,OH)3
Description: Erroneously reported by dealer to come from this mine, gaudefroyite has not been recorded here, datasheets and references from von Bezing and Cairncross et al and personal communitcations cross-checked by Debbie Woolf.
Gypsum
Formula: CaSO4 · 2H2O
Reference: Rob Lavinsky photo; Peacor, D. R., Dunn, P. J., & Duggan, M. (1983). Sturmanite, a ferric iron, boron analogue of ettringite. Canadian Mineralogist, 21, 705-709.
Hematite
Formula: Fe2O3
Reference: Cairncross, B., (2004), Field Guide to Rocks & Minerals of Southern Africa. Struik Publishers, Cape Town, South Africa.; Peacor, D. R., Dunn, P. J., & Duggan, M. (1983). Sturmanite, a ferric iron, boron analogue of ettringite. Canadian Mineralogist, 21, 705-709.
Inesite
Formula: Ca2(Mn,Fe)7Si10O28(OH)2 · 5H2O
Reference: Rock Currier photo
Lithiophorite
Formula: (Al,Li)MnO2(OH)2
Reference: Minerals of South Africa
Manganite
Formula: Mn3+O(OH)
Reference: Cors de Brun photo
Marokite
Formula: CaMn3+2O4
Reference: de Villiers, P.R., Herbstein, F.H. (1968) Second occurrence of marokite. American Mineralogist: 53: 495.
Opal
Formula: SiO2 · nH2O
Reference: Am Min 53:495
Portlandite
Formula: Ca(OH)2
Reference: Minerals of South Africa
Pyrolusite
Formula: Mn4+O2
Reference: Minerals of South Africa
Quartz
Formula: SiO2
Reference: Minerals of South Africa
Quartz var: Chalcedony
Formula: SiO2
Reference: Minerals of South Africa
Rhodochrosite
Formula: MnCO3
Reference: Jewel Tunnel Imports specimen (1978).
Sturmanite ? (TL)
Formula: Ca6(Fe3+,Al,Mn3+)2(SO4)2[B(OH)4](OH)12 · 25H2O
Description: Although this locality is the type locality for the mineral, it is believed that the actual type locality is the Wessels mine due to an error in labeling the type specimen. No subsequent specimens containing sturmanite or other minerals on the type specimen have been found since, similar material from Wessels was found from 5 pockets in the years 1978-1982.
Reference: PEACOR, D.R., DUNN, P.J. & DUGGAN, M. (1983): Sturmanite, a ferric iron, boron analogue of ettringite. Canadian Mineralogist 21, 705-709. HOCHLEITNER, R. (1986): Sturmanit und Ettringit aus den Kalahari-Manganfeldern. Lapis, Jg. 10, Nr. 10, 19-24. VON BENZIG, K.L., DIXON, R.D., POHL, D. & CAVALLO, G. (1991): The Kalahari manganese field: An update. Mineralogical Record 22, 292-293. CAIRNCROSS, B. & DIXON, R. (1995): Minerals of South Africa. Published by The Geological Society of South Africa, Johannesburg, 60-66 and 244-245.
Xonotlite
Formula: Ca6(Si6O17)(OH)2
Reference: Rob Lavinsky photo

List of minerals arranged by Strunz 10th Edition classification

Group 4 - Oxides and Hydroxides
'Bixbyite'4.CB.10Mn3+2O3
Cryptomelane4.DK.05aK(Mn4+7Mn3+)O16
Hematite4.CB.05Fe2O3
Lithiophorite4.FE.25(Al,Li)MnO2(OH)2
Manganite4.FD.15Mn3+O(OH)
Marokite4.BC.05CaMn3+2O4
Opal4.DA.10SiO2 · nH2O
Portlandite4.FE.05Ca(OH)2
Pyrolusite4.DB.05Mn4+O2
Quartz4.DA.05SiO2
var: Chalcedony4.DA.05SiO2
Group 5 - Nitrates and Carbonates
'Calcite'5.AB.05CaCO3
Rhodochrosite5.AB.05MnCO3
Group 6 - Borates
Gaudefroyite ?6.AB.60Ca4Mn3+2-3(BO3)3(CO3)(O,OH)3
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
'Baryte'7.AD.35BaSO4
'Celestine'7.AD.35SrSO4
Ettringite ?7.DG.15Ca6Al2(SO4)3(OH)12 · 26H2O
Gypsum7.CD.40CaSO4 · 2H2O
Sturmanite ? (TL)7.DG.15Ca6(Fe3+,Al,Mn3+)2(SO4)2[B(OH)4](OH)12 · 25H2O
Group 9 - Silicates
'Aegirine'9.DA.25NaFe3+Si2O6
'Andradite'9.AD.25Ca3Fe3+2(SiO4)3
'Banalsite'9.FA.60Na2BaAl4Si4O16
'Braunite'9.AG.05Mn2+Mn3+6(SiO4)O8
'Braunite-II' (TL)9.AG.05CaMn3+14(SiO4)O20
Cymrite9.EG.05BaAl2Si2(O,OH)8 · H2O
Inesite9.DL.05Ca2(Mn,Fe)7Si10O28(OH)2 · 5H2O
Xonotlite9.DG.35Ca6(Si6O17)(OH)2
Unclassified Minerals, Rocks, etc.
'Apatite'-

List of minerals arranged by Dana 8th Edition classification

Group 4 - SIMPLE OXIDES
A2X3
Bixbyite4.3.7.2Mn3+2O3
Hematite4.3.1.2Fe2O3
AX2
Pyrolusite4.4.1.4Mn4+O2
Group 6 - HYDROXIDES AND OXIDES CONTAINING HYDROXYL
XO(OH)
Manganite6.1.3.1Mn3+O(OH)
X(OH)2
Portlandite6.2.1.4Ca(OH)2
Miscellaneous
Lithiophorite6.4.1.1(Al,Li)MnO2(OH)2
Group 7 - MULTIPLE OXIDES
AB2X4
Marokite7.2.10.1CaMn3+2O4
(AB)2X3
Braunite7.5.1.3Mn2+Mn3+6(SiO4)O8
'Braunite-II' (FRL)7.5.1.3CaMn3+14(SiO4)O20
AB8X16
Cryptomelane7.9.1.2K(Mn4+7Mn3+)O16
Group 14 - ANHYDROUS NORMAL CARBONATES
A(XO3)
Calcite14.1.1.1CaCO3
Rhodochrosite14.1.1.4MnCO3
Group 27 - COMPOUND BORATES
Miscellaneous
Gaudefroyite ?27.1.2.1Ca4Mn3+2-3(BO3)3(CO3)(O,OH)3
Group 28 - ANHYDROUS ACID AND NORMAL SULFATES
AXO4
Baryte28.3.1.1BaSO4
Celestine28.3.1.2SrSO4
Group 29 - HYDRATED ACID AND NORMAL SULFATES
AXO4·xH2O
Gypsum29.6.3.1CaSO4 · 2H2O
Group 31 - HYDRATED SULFATES CONTAINING HYDROXYL OR HALOGEN
Miscellaneous
Ettringite ?31.10.2.1Ca6Al2(SO4)3(OH)12 · 26H2O
Group 32 - COMPOUND SULFATES
Hydrated Compound Sulfates containing Hydroxyl or Halogen
Sturmanite ? (TL)32.4.4.2Ca6(Fe3+,Al,Mn3+)2(SO4)2[B(OH)4](OH)12 · 25H2O
Group 51 - NESOSILICATES Insular SiO4 Groups Only
Insular SiO4 Groups Only with cations in [6] and >[6] coordination
Andradite51.4.3b.1Ca3Fe3+2(SiO4)3
Group 65 - INOSILICATES Single-Width,Unbranched Chains,(W=1)
Single-Width Unbranched Chains, W=1 with chains P=2
Aegirine65.1.3c.2NaFe3+Si2O6
Group 66 - INOSILICATES Double-Width,Unbranched Chains,(W=2)
Amphiboles - Ca-Na subgroup
Inesite66.3.3.1Ca2(Mn,Fe)7Si10O28(OH)2 · 5H2O
Xonotlite66.3.1.1Ca6(Si6O17)(OH)2
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Si Tetrahedral Frameworks - SiO2 with H2O and organics
Opal75.2.1.1SiO2 · nH2O
Group 76 - TECTOSILICATES Al-Si Framework
Al-Si Framework with Al-Si frameworks
Banalsite76.1.6.1Na2BaAl4Si4O16
Group 78 - Unclassified Silicates
Miscellaneous
Cymrite78.1.3.1BaAl2Si2(O,OH)8 · H2O
Unclassified Minerals, Rocks, etc.
'Apatite'-
Quartz
var: Chalcedony
-SiO2

List of minerals for each chemical element

HHydrogen
H CymriteBaAl2Si2(O,OH)8 · H2O
H EttringiteCa6Al2(SO4)3(OH)12 · 26H2O
H GypsumCaSO4 · 2H2O
H InesiteCa2(Mn,Fe)7Si10O28(OH)2 · 5H2O
H Lithiophorite(Al,Li)MnO2(OH)2
H ManganiteMn3+O(OH)
H OpalSiO2 · nH2O
H PortlanditeCa(OH)2
H SturmaniteCa6(Fe3+,Al,Mn3+)2(SO4)2[B(OH)4](OH)12 · 25H2O
H XonotliteCa6(Si6O17)(OH)2
LiLithium
Li Lithiophorite(Al,Li)MnO2(OH)2
BBoron
B GaudefroyiteCa4Mn3+2-3(BO3)3(CO3)(O,OH)3
B SturmaniteCa6(Fe3+,Al,Mn3+)2(SO4)2[B(OH)4](OH)12 · 25H2O
CCarbon
C CalciteCaCO3
C GaudefroyiteCa4Mn3+2-3(BO3)3(CO3)(O,OH)3
C RhodochrositeMnCO3
OOxygen
O AegirineNaFe3+Si2O6
O AndraditeCa3Fe23+(SiO4)3
O BanalsiteNa2BaAl4Si4O16
O BaryteBaSO4
O BixbyiteMn23+O3
O BrauniteMn2+Mn63+(SiO4)O8
O Braunite-IICaMn143+(SiO4)O20
O CalciteCaCO3
O CelestineSrSO4
O Quartz (var: Chalcedony)SiO2
O CryptomelaneK(Mn74+Mn3+)O16
O CymriteBaAl2Si2(O,OH)8 · H2O
O EttringiteCa6Al2(SO4)3(OH)12 · 26H2O
O GaudefroyiteCa4Mn3+2-3(BO3)3(CO3)(O,OH)3
O GypsumCaSO4 · 2H2O
O HematiteFe2O3
O InesiteCa2(Mn,Fe)7Si10O28(OH)2 · 5H2O
O Lithiophorite(Al,Li)MnO2(OH)2
O ManganiteMn3+O(OH)
O MarokiteCaMn23+O4
O OpalSiO2 · nH2O
O PortlanditeCa(OH)2
O PyrolusiteMn4+O2
O QuartzSiO2
O RhodochrositeMnCO3
O SturmaniteCa6(Fe3+,Al,Mn3+)2(SO4)2[B(OH)4](OH)12 · 25H2O
O XonotliteCa6(Si6O17)(OH)2
NaSodium
Na AegirineNaFe3+Si2O6
Na BanalsiteNa2BaAl4Si4O16
AlAluminium
Al BanalsiteNa2BaAl4Si4O16
Al CymriteBaAl2Si2(O,OH)8 · H2O
Al EttringiteCa6Al2(SO4)3(OH)12 · 26H2O
Al Lithiophorite(Al,Li)MnO2(OH)2
Al SturmaniteCa6(Fe3+,Al,Mn3+)2(SO4)2[B(OH)4](OH)12 · 25H2O
SiSilicon
Si AegirineNaFe3+Si2O6
Si AndraditeCa3Fe23+(SiO4)3
Si BanalsiteNa2BaAl4Si4O16
Si BrauniteMn2+Mn63+(SiO4)O8
Si Braunite-IICaMn143+(SiO4)O20
Si Quartz (var: Chalcedony)SiO2
Si CymriteBaAl2Si2(O,OH)8 · H2O
Si InesiteCa2(Mn,Fe)7Si10O28(OH)2 · 5H2O
Si OpalSiO2 · nH2O
Si QuartzSiO2
Si XonotliteCa6(Si6O17)(OH)2
SSulfur
S BaryteBaSO4
S CelestineSrSO4
S EttringiteCa6Al2(SO4)3(OH)12 · 26H2O
S GypsumCaSO4 · 2H2O
S SturmaniteCa6(Fe3+,Al,Mn3+)2(SO4)2[B(OH)4](OH)12 · 25H2O
KPotassium
K CryptomelaneK(Mn74+Mn3+)O16
CaCalcium
Ca AndraditeCa3Fe23+(SiO4)3
Ca Braunite-IICaMn143+(SiO4)O20
Ca CalciteCaCO3
Ca EttringiteCa6Al2(SO4)3(OH)12 · 26H2O
Ca GaudefroyiteCa4Mn3+2-3(BO3)3(CO3)(O,OH)3
Ca GypsumCaSO4 · 2H2O
Ca InesiteCa2(Mn,Fe)7Si10O28(OH)2 · 5H2O
Ca MarokiteCaMn23+O4
Ca PortlanditeCa(OH)2
Ca SturmaniteCa6(Fe3+,Al,Mn3+)2(SO4)2[B(OH)4](OH)12 · 25H2O
Ca XonotliteCa6(Si6O17)(OH)2
MnManganese
Mn BixbyiteMn23+O3
Mn BrauniteMn2+Mn63+(SiO4)O8
Mn Braunite-IICaMn143+(SiO4)O20
Mn CryptomelaneK(Mn74+Mn3+)O16
Mn GaudefroyiteCa4Mn3+2-3(BO3)3(CO3)(O,OH)3
Mn InesiteCa2(Mn,Fe)7Si10O28(OH)2 · 5H2O
Mn Lithiophorite(Al,Li)MnO2(OH)2
Mn ManganiteMn3+O(OH)
Mn MarokiteCaMn23+O4
Mn PyrolusiteMn4+O2
Mn RhodochrositeMnCO3
Mn SturmaniteCa6(Fe3+,Al,Mn3+)2(SO4)2[B(OH)4](OH)12 · 25H2O
FeIron
Fe AegirineNaFe3+Si2O6
Fe AndraditeCa3Fe23+(SiO4)3
Fe HematiteFe2O3
Fe SturmaniteCa6(Fe3+,Al,Mn3+)2(SO4)2[B(OH)4](OH)12 · 25H2O
SrStrontium
Sr CelestineSrSO4
BaBarium
Ba BanalsiteNa2BaAl4Si4O16
Ba BaryteBaSO4
Ba CymriteBaAl2Si2(O,OH)8 · H2O

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

Quaternary - Tertiary
0 - 66 Ma



ID: 3185837
Cenozoic sedimentary rocks

Age: Cenozoic (0 - 66 Ma)

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]

Cenozoic
0 - 66 Ma



ID: 2233217
Kalahari Group

Age: Cenozoic (0 - 66 Ma)

Stratigraphic Name: Kalahari Group

Description: Superficial deposits comprising gravels, clays, sandstone, silcrete, calcrete and aeolian sand

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

Pleistocene - Paleogene
0.0117 - 66 Ma



ID: 3306660

Age: Cenozoic (0.0117 - 66 Ma)

Lithology: Sedimentary

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

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)
de Villiers, P.R., Herbstein, F.H. (1968) Second occurrence of marokite. American Mineralogist: 53: 495.
Peacor, D.R., Dunn, P.J., Duggan, M. (1983) Sturmanite, a ferric iron, boron analogue of ettringite. Canadian Mineralogist: 21: 705-709.
Mining Annual review (1985) 90.
Hochleitner, R. (1986) Sturmanit und Ettringit aus den Kalahari-Manganfeldern. Lapis: 10(10): 19-24.
Von Bezing, K. L. et al. (1991) The Kalahari manganese field: An Update, Mineralogical Record 22(4) 279-302.
Weiner, K.L., Hochleitner, R. (1994) Sturmanit - Steckbrief. Lapis: 19(2): 9-11.
Cairncross, B., Dixon, R. (1995) Minerals of South Africa. The Geological Society of South Africa, Linden 2014, RSA.
Cairncross, B., Beukes, N., Gutzmer, J. (1997) The Manganese Adventure, The South African Manganese Fields. Associated Ore & Metal Corporation Limited, Johannesburg, Republic of South Africa.
Cairncross, B., Beukes, N.J. (2013) The Kalahari Manganese Field, the adventure continues. Struik Nature Publishers, Cape Town, South Africa.


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