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N'Chwaning II Mine, N'Chwaning Mines, Kuruman, Kalahari manganese field, Northern Cape Province, South Africa

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Detailed Mineral List:


Aegirine
Formula: NaFe3+Si2O6
Habit: euhedral
Colour: black
Description: Until late 2011 aegirine was found as gangue mineral, now found in association with marshallsussmanite.
Reference: Cairncross, B., and Beukes, N. J., (2013) The Kalahari Manganese Field, the adventure continues. Struik Nature Publishers, Cape Town, South Africa, pp 150.
Afwillite
Formula: Ca3(HSiO4)2 · 2H2O
Reference: Minerals of South Africa
Andradite
Formula: Ca3Fe3+2(SiO4)3
Reference: Minerals of South Africa
Aragonite
Formula: CaCO3
Reference: Minerals of South Africa
Baryte
Formula: BaSO4
Description: Tabular crystals up to 10cm on edge are recorded from here.
Reference: Cairncross, B. and Dixon, R., (1995) Minerals of South Africa. The Geological Society of South Africa: 186.
Bementite
Formula: Mn7Si6O15(OH)8
Description: associated with andradite garnet
Reference: Cairncross, B., and Dixon, R., (1995) Minerals of South Africa. The Geological Society of South Africa, Linden 2014, RSA
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; Cairncross, B., and Dixon, R., (1995) Minerals of South Africa. The Geological Society of South Africa, Linden 2014, RSA
Braunite
Formula: Mn2+Mn3+6(SiO4)O8
Reference: Cairncross B. and Beukes, N.J. (2013). The Kalahari Manganese Field: the Adventure Continues. Struik Nature, Cape Town, South Africa, 384 pages.
'Braunite-II'
Formula: CaMn3+14(SiO4)O20
Description: Braunite II was first discovered in 1945 at Black Rock and described as ferrianbraunite. The phase was renamed braunite II by De Villiers and Herbstein in 1967 and its crystal structure was determined by De Villiers in 1980. Metallic-grey braunite II crystals have come from Wessels, Black Rock (up to two centimetres) and N’Chwaning II. The crystals are typically bipyramidal with complex terminations. In 1995, crystals up to three centimetres were found at Wessels mine, and a few very rare larger crystals were also collected at the time. These were associated with andradite garnet, hausmannite and occasionally yellow ettringite. Braunite II is not listed as a recognised species in the IMA RRUFF database. See De Villiers (1945), De Villiers and Herbstein (1967), De Villiers (1970), De Villiers (1980) and De Villiers (1989) for details.
Reference: De Villiers, J.E. (1945b). Some minerals occurring in South African manganese deposits. Transactions of the Geological Society of South Africa, 48, 17–25. De Villiers, P.R. and Herbstein, F.H. (1967). Distinction between two members of the braunite group. American Mineralogist, 52, 20–30. De Villiers, P.R. (1970). The geology and mineralogy of the Kalahari manganese-field north of Sishen, Cape Province. Memoir of the Geological Survey of South Africa, No. 59, 84 pages. De Villiers, J.P.R. (1980). The crystal structure of braunite II and its relation to bixbyite and braunite. American Mineralogist, 65, 756–765. De Villiers, J.P.R. (1989). Stacking variations and nonstoichiometry in the bixbyite-braunite polysomatic mineral group. American Mineralogist, 74, 1325–1336. Cairncross, B., Beukes, N. and Gutzmer, J. (1997): The manganese adventure – the South African manganese fields. Associated Ore & Metal Corporation Limited, Johannesburg, Republic of South Africa, 236 pp. Cairncross, B. and Beukes, N.J. (2013). The Kalahari Manganese Field: the adventure continues. Struik Nature, Cape Town, South Africa, 384 pages.
Brucite
Formula: Mg(OH)2
Reference: Cairncross, B. and Dixon, R., (1995) Minerals of South Africa. The Geological Society of South Africa: 191.
Bultfonteinite
Formula: Ca2(HSiO4)F · H2O
Reference: Lapis (2004): 29(9):12; Bonazzi, P., Bindi, L., Medenbach, O., Pagano, R., Lampronti, Menchetti, S. (2007): Olmiite, CaMn[SiO3(OH)](OH), the Mn-dominant analogue of poldervaartite, a new mineral species from Kalahari manganese fields (Republic of South Africa), Mineralogical Magazine, 71, 193-291.
Bustamite
Formula: CaMn2+(Si2O6)
Reference: Minerals of South Africa
Calcite
Formula: CaCO3
Reference: Bruce Cairncross (2000) The Desmond Sacco Collection
Caryopilite
Formula: Mn2+3Si2O5(OH)4
Reference: Minerals of South Africa
Celestine
Formula: SrSO4
Habit: Botryoidal, divergent sprays, also slightly curved crystals, columnar.
Colour: Pearly blue, white to colourless.
Description: Found in association with baryte, calcite, hydroxyapophyllite and pectolite or only with calcite at this mine, has also produced columnar crystals up to 4cm length embedded in caryopilite.
Reference: Cairncross, B. and Dixon, R., (1995) Minerals of South Africa. The Geological Society of South Africa: 194-195. Cairncross, B. (2004) Field Guide To Rocks & Minerals Of Southern Africa: 66. Minerals of South Africa; Bonazzi, P., Bindi, L., Medenbach, O., Pagano, R., Lampronti, Menchetti, S. (2007): Olmiite, CaMn[SiO3(OH)](OH), the Mn-dominant analogue of poldervaartite, a new mineral species from Kalahari manganese fields (Republic of South Africa), Mineralogical Magazine, 71, 193-291.
Charlesite ?
Formula: Ca6(Al,Si)2(SO4)2[B(OH)4](OH,O)12 · 26H2O
Description: No formal testing known
Reference: Minerals of South Africa
'Chlorite Group'
Reference: Minerals of South Africa
Cinnabar
Formula: HgS
Habit: microcrystals
Colour: red
Description: Originally found in the late 1990's on bladed hausmannite, XRD confirmed both. Recent finds of calcite with cinnabar inclusions have been identified.
Reference: Cairncross, B., and Beukes, N. J., (2013) The Kalahari Manganese Field, the adventure continues. Struik Nature Publishers, Cape Town, South Africa, 192 pp.
Clinochlore
Formula: Mg5Al(AlSi3O10)(OH)8
Reference: Minerals of South Africa
Copper
Formula: Cu
Description: Associated with calcite and ettringite
Reference: Cairncross photo ID 729305
Creedite
Formula: Ca3SO4Al2F8(OH)2 · 2H2O
Habit: micaceous
Colour: white
Reference: Minerals of South Africa
Datolite
Formula: Ca(HBSiO5)
Reference: Minerals of South Africa
Despujolsite
Formula: Ca3Mn4+(SO4)2(OH)6 · 3H2O
Reference: Cairncross photo ID 729306
Diaspore
Formula: AlO(OH)
Reference: dan weinrich
Diopside
Formula: CaMgSi2O6
Reference: Minerals of South Africa
Ettringite
Formula: Ca6Al2(SO4)3(OH)12 · 26H2O
Reference: Minerals of South Africa + Hochleitner, R. (1986). Sturmanit und Ettringit aus den Kalahari-Manganfeldern. LAPIS 11 (10), 19-24
Friedelite
Formula: Mn2+8Si6O15(OH,Cl)10
Reference: Minerals of South Africa
Gageite
Formula: Mn21(Si4O12)2O3(OH)20
Reference: Cairncross, B., and Dixon, R., (1995) Minerals of South Africa. The Geological Society of South Africa, Linden 2014, RSA;
Galena
Formula: PbS
Reference: Minerals of South Africa
Gaudefroyite
Formula: Ca4Mn3+2-3(BO3)3(CO3)(O,OH)3
Habit: Prismatic, hair-like, fibrous.
Colour: Black, copper-brown
Description: Largest crystals were up to 5cm, specimens of 1cm are common. Associated minerals are andradite, calcite, ettringite, hausmannite and hematite. The bronze hair-like specimens have been found in association with baryte, calcite, gypsum, hausmannite and hematite.
Reference: Cairncross, B., and Dixon, R., (1995) Minerals of South Africa. The Geological Society of South Africa, Linden 2014, RSA; Gutzmer, J. (1996). Genesis and alteration of the Kalahari and Postmasburg manganese deposits, Griqualand West, South Africa (Doctoral dissertation, Rand Afrikaans University); Cairncross, B., and Beukes, N. J., (2013) The Kalahari Manganese Field, the adventure continues. Struik Nature Publishers, Cape Town, South Africa
Glauconite
Formula: (K,Na)(Mg,Fe2+,Fe3+)(Fe3+,Al)(Si,Al)4O10(OH)2
Reference: Minerals of South Africa
Goethite
Formula: α-Fe3+O(OH)
Reference: Minerals of South Africa
Gonyerite
Formula: (Mn2+,Mg)5Fe3+(Fe3+Si3O10)(OH)8
Reference: Cairncross, B., and Beukes, N. J., (2013) The Kalahari Manganese Field, the adventure continues. Struik Nature Publishers, Cape Town, South Africa, p 216;
Gowerite
Formula: Ca[B5O8(OH)][B(OH)3] · 3H2O
Reference: Minerals of South Africa
Grossular
Formula: Ca3Al2(SiO4)3
Description: Recorded as small grains.
Reference: Cairncross, B. and Dixon, R., (1995) Minerals of South Africa. The Geological Society of South Africa. 214.
Grossular var: Hibschite
Formula: Ca3Al2(SiO4)3-x(OH)4x
Description: Recorded as small grains.
Reference: Cairncross, B. and Dixon, R., (1995) Minerals of South Africa. The Geological Society of South Africa. 214.
Groutite
Formula: Mn3+O(OH)
Reference: Minerals of South Africa
Guidottiite (TL)
Formula: Mn2Fe3+(Fe3+SiO5)(OH)4
Type Locality: N'Chwaning II Mine, N'Chwaning Mines, Kuruman, Kalahari manganese field, Northern Cape Province, South Africa
Reference: Wahle, M.W., Bujnowski, T.J., Guggenheim, S., Kogure, T. (2010): Guidottiite, the Mn-analogue of cronstedtite: A new serpentine group mineral from South Africa. Clays and Clay Minerals, 58, 364-378.
Gypsum
Formula: CaSO4 · 2H2O
Reference: Minerals of South Africa
Hausmannite
Formula: Mn2+Mn3+2O4
Reference: Minerals of South Africa
Hematite
Formula: Fe2O3
Reference: Minerals of South Africa; Bonazzi, P., Bindi, L., Medenbach, O., Pagano, R., Lampronti, Menchetti, S. (2007): Olmiite, CaMn[SiO3(OH)](OH), the Mn-dominant analogue of poldervaartite, a new mineral species from Kalahari manganese fields (Republic of South Africa), Mineralogical Magazine, 71, 193-291.
Henritermierite
Formula: Ca3(Mn3+,Al)2(SiO4)2(OH)4
Colour: orange
Description: to 3mm
Reference: Minerals of South Africa
Hydroxyapophyllite-(K)
Formula: KCa4(Si8O20)(OH,F) · 8H2O
Reference: Minerals of South Africa
Inesite
Formula: Ca2(Mn,Fe)7Si10O28(OH)2 · 5H2O
Reference: Minerals of South Africa
Jacobsite
Formula: Mn2+Fe3+2O4
Habit: octahedrons to 8mm
Reference: Minerals of South Africa
Jouravskite
Formula: Ca3Mn4+(SO4)(CO3)(OH)6 · 12H2O
Reference: Minerals of South Africa
Kenotobermorite (TL)
Formula: [Ca4Si6O15(OH)2·2H2O]·3H2O
Type Locality: N'Chwaning II Mine, N'Chwaning Mines, Kuruman, Kalahari manganese field, Northern Cape Province, South Africa
Description: The type specimen was erronously stated as comiing from the Wessels mine in Merlino et al (2001), and corrected in Biagioni et al (2015).
Reference: Merlino S, Bonaccorsi E, Armbruster T (2001) The real structure of tobermorite 11Å: normal and anomalous forms, OD character and polytypic modification. European Journal of Mineralogy 13, 577-590 ; Biagioni, C., Merlino, S., Bonaccorsi, E. (2015): The tobermorite supergroup: a new nomenclature. Mineralogical Magazine, 79, 485-495
'Kenotobermorite-4O'
Reference: Merlino S, Bonaccorsi E, Armbruster T (2001) The real structure of tobermorite 11Å: normal and anomalous forms, OD character and polytypic modification. European Journal of Mineralogy 13, 577-590; Biagioni, C., Merlino, S., Bonaccorsi, E. (2015): The tobermorite supergroup: a new nomenclature. Mineralogical Magazine, 79, 485-495
Kutnohorite
Formula: Ca(Mn,Mg,Fe)(CO3)2
Reference: Minerals of South Africa
Lavinskyite ?
Formula: K(Li,Cu,Mg,Na)2Cu6(Si4O11)2(OH)4
Reference: Label from Kalahari Minerals.
Lepidocrocite
Formula: γ-Fe3+O(OH)
Reference: Minerals of South Africa
Leucophoenicite
Formula: Mn2+7(SiO4)3(OH)2
Reference: Cairncross, B. and Dixon, R., (1995) Minerals of South Africa. The Geological Society of South Africa.
Lizardite
Formula: Mg3(Si2O5)(OH)4
Reference: Minerals of South Africa
Manganite
Formula: Mn3+O(OH)
Reference: Minerals of South Africa
Manganvesuvianite (TL)
Formula: Ca19Mn3+(Al,Mn3+,Fe3+)10(Mg,Mn2+)2(Si2O7)4(SiO4)10O(OH)9
Type Locality: N'Chwaning II Mine, N'Chwaning Mines, Kuruman, Kalahari manganese field, Northern Cape Province, South Africa
Reference: T. Armbruster et al. (2002) Mineralogical Magazine 66, 137-150
Marcasite
Formula: FeS2
Reference: Minerals of South Africa
Marokite
Formula: CaMn3+2O4
Reference: Minerals of South Africa
Marshallsussmanite
Formula: NaCaMnSi3O8(OH)
Colour: Light pink to deep pink
Description: Discovered in 2011 from Wessels and N'Chwaning II mines.
Reference: Cairncross, B. and Beukes, N. J., (2013) The Kalahari Manganese Field, the adventure continues. Struik Nature Publishers, Cape Town, South Africa.
Mozartite
Formula: CaMn3+(SiO4)(OH)
Reference: Minerals of South Africa
Nchwaningite (TL)
Formula: Mn2+2(SiO3)(OH)2 · H2O
Type Locality: N'Chwaning II Mine, N'Chwaning Mines, Kuruman, Kalahari manganese field, Northern Cape Province, South Africa
Description: Pocket near fault intersection in Section 27 South
Reference: [Amer.Min.(1995) 80, 377-386; MinRec 27:203-204]
Olmiite (TL)
Formula: CaMn2+[SiO3(OH)](OH)
Type Locality: N'Chwaning II Mine, N'Chwaning Mines, Kuruman, Kalahari manganese field, Northern Cape Province, South Africa
Reference: Bonazzi, P., Bindi, L., Medenbach, O., Pagano, R., Lampronti, Menchetti, S. (2007): Olmiite, CaMn[SiO3(OH)](OH), the Mn-dominant analogue of poldervaartite, a new mineral species from Kalahari manganese fields (Republic of South Africa), Mineralogical Magazine, 71, 193-291.
Orlymanite
Formula: Ca4Mn3Si8O20(OH)6 · 2H2O
Description: Associated with Gonyerite spheres.
Reference: Cairncross, B., and Beukes, N. J., (2013) The Kalahari Manganese Field, the adventure continues. Struik Nature Publishers, Cape Town, South Africa, p 216;
Oyelite
Formula: Ca10Si8B2O29 · 12.5H2O
Reference: Minerals of South Africa
Pectolite
Formula: NaCa2Si3O8(OH)
Reference: Cairncross, B. and Dixon, R., (1995), Minerals of South Africa. The Geological Society of South Africa: 229
Phlogopite
Formula: KMg3(AlSi3O10)(OH)2
Reference: Minerals of South Africa
Poldervaartite
Formula: CaCa[SiO3(OH)](OH)
Description: See Min Rec Article - all believed to be olmiite
Reference: • Cairncross, B., Gutzmer, J. & Pretorius, A. (2002): Spektakulärer Neufund: Poldervaartit aus der N'Chwaning II - Mine, Kalahari, Südafrika. Lapis, 27(5), 30-34; Bonazzi, P., Bindi, L., Medenbach, O., Pagano, R., Lampronti, Menchetti, S. (2007): Olmiite, CaMn[SiO3(OH)](OH), the Mn-dominant analogue of poldervaartite, a new mineral species from Kalahari manganese fields (Republic of South Africa), Mineralogical Magazine, 71, 193-291.. Pagano et al (2008) Mineralogical Record 39:373-381
Portlandite
Formula: Ca(OH)2
Reference: Minerals of South Africa
Prehnite
Formula: Ca2Al2Si3O10(OH)2
Reference: Cairncross B., Tsikos H. & Harris C. (2000) Prehnite from the Kalahari Mn field, South Africa, and its possible implications. South African Journal of Geology 103, 231-236.
Pyrite
Formula: FeS2
Reference: Minerals of South Africa
Pyrochroite
Formula: Mn(OH)2
Reference: [MinRec 22:289]
Quartz
Formula: SiO2
Reference: Minerals of South Africa
Rhodochrosite
Formula: MnCO3
Reference: Minerals of South Africa
Richterite
Formula: {Na}{NaCa}{Mg5}(Si8O22)(OH)2
Reference: Minerals of South Africa
Ruizite
Formula: Ca2Mn3+2[Si4O11(OH)2](OH)2·2H2O
Reference: Minerals of South Africa
Saponite
Formula: Ca0.25(Mg,Fe)3((Si,Al)4O10)(OH)2 · nH2O
Reference: Minerals of South Africa
Shigaite
Formula: Mn6Al3(OH)18[Na(H2O)6][SO4]2 · 6H2O
Description: It appears there was a typo in the reference citing this mine, subsequent references clearly state shigaite is from N'Chwaning I mine and personal communications with Bruce Cairncross confirm this.
Reference: Gutzmer, J. (1996). Genesis and alteration of the Kalahari and Postmasburg manganese deposits, Griqualand West, South Africa (Doctoral dissertation, Rand Afrikaans University).
Sphalerite
Formula: ZnS
Reference: Minerals of South Africa
Sturmanite
Formula: Ca6(Fe3+,Al,Mn3+)2(SO4)2[B(OH)4](OH)12 · 25H2O
Reference: Minerals of South Africa + Hochleitner, R. (1986). Sturmanit und Ettringit aus den Kalahari-Manganfeldern; Lapis: 11(10): 19-24; Bonazzi, P., Bindi, L., Medenbach, O., Pagano, R., Lampronti, Menchetti, S. (2007): Olmiite, CaMn[SiO3(OH)](OH), the Mn-dominant analogue of poldervaartite, a new mineral species from Kalahari manganese fields (Republic of South Africa), Mineralogical Magazine, 71, 193-291.
Sugilite
Formula: K(Na,□)2Li3(Fe,Mn,Al,Zr)2[Si12O30]
Reference: Minerals of South Africa
Sussexite
Formula: Mn2+BO2(OH)
Reference: Minerals of South Africa
Tephroite
Formula: Mn2+2SiO4
Reference: Minerals of South Africa
Thaumasite
Formula: Ca3(SO4)[Si(OH)6](CO3) · 12H2O
Description: Crystals to 5cm.
Reference: Minerals of South Africa
Todorokite
Formula: (Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
Description: Found as tufts of needles enclosed in gypsum.
Reference: Von Bezing, K. L. et al. (1991) The Kalahari manganese field: An Update, Mineralogical Record 22(4) 279-302; Cairncross, B., and Dixon, R., (1995) Minerals of South Africa. The Geological Society of South Africa, Linden 2014, RSA, pg 249
Vesuvianite
Formula: (Ca,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10
Reference: Minerals of South Africa
Xonotlite
Formula: Ca6(Si6O17)(OH)2
Reference: Minerals of South Africa

References

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Hochleitner, R. (1986) Sturmanit und Ettringit aus den Kalahari-Manganfeldern. LAPIS 11 (10), 19-24.
Beukes, G.J., De Bruiyn, H. and Van der Westhuizen, W.A. (1993) Gaudefroyite from the Kalahari manganese field, South Africa. Neues Jahrbuch Mineralogie, Monatshefte, 385–392.
Gutzmer, J. (1994) Hydrothermale Alteration von Manganerzen der Nchwaning Mine, Kalahari Manganerzfeld, Suedafrika. Diploma dissertation (unpublished). Clausthal University of Technology, 158 pages.
Gutzmer, J. (1994) Hydrothermale Alteration von Manganerzen der Nchwaning Mine, Kalahari Manganerzfeld, Suedafrika. Mitteilungsblatt. Clausthal University of Technology, 53–54.
Cairncross, B., and Dixon, R. (1995) Minerals of South Africa. The Geological Society of South Africa, Linden 2014, RSA.
Nyfeler, D., Armbruster, T., Dixon, R. and Bermanec, V. (1995) Nchwaningite, Mn2+2SiO3(OH)2•H2O, a new pyroxene related chain silicate from the Nchwaning mine, Kalahari manganese field, South Africa. American Mineralogist, 80, 377–386.
Cairncross, B., Beukes, N. and Gutzmer, J. (1997) The Manganese Adventure – The South African Manganese Fields. Associated Ore & Metal Corporation Limited, Johannesburg, Republic of South Africa.
Cairncross, B., Tsikos, H. and Harris, C. (2000) Prehnite from the Kalahari manganese field, South Africa, and its possible implications. South African Journal of Geology, 103, 231–236.
Cairncross, B., Gutzmer, J. and Pretorius, A. (2002) Spektakulärer Neufund: Poldervaartit aus der N’Chwaning II-Mine, Kalahari, Südafrika. Lapis, 27, 30–34.
Cairncross, B. (2004) Field Guide To Rocks & Minerals Of Southern Africa.
Bonazzi, P., Bindi, L., Medenbach, O., Pagano, R., Lampronti, Menchetti, S. (2007) Olmiite, CaMn[SiO3(OH)](OH), the Mn-dominant analogue of poldervaartite, a new mineral species from Kalahari manganese fields (Republic of South Africa), Mineralogical Magazine, 71, 193-291.
Cairncross, B., and Beukes, N. J., (2013) The Kalahari Manganese Field, the adventure continues. Struik Nature Publishers, Cape Town, South Africa.

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