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Sturmanite

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N'Chwaning I Mine, N'Chwaning Mines, Kalahari manganese fields, Northern Cape Province, South Africa
© Wright's Rock Shop

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Formula:
Ca
 
6
(Fe
3+
 
,Al,Mn
3+
 
)
 
2
[(OH)
 
12
|B(OH)
 
4
|(SO
 
4
)
 
2
] · 25H
 
2
O
System:TrigonalColour:Bright Yellow to amber
Lustre:Vitreous, GreasyHardness:2½
Name:For B. Darko Sturman (b. 1937), Department of Mineralogy & Geology, Royal Ontario Museum, Toronto, Ontario, Canada.


Ettringite Group.

Classification of Sturmanite

IMA status:Approved 1981
Explanation of status:Although the Black Rock mine 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).
Strunz 8th edition ID:6/D.13-50
Strunz 9th edition ID:7.DG.15
Nickel-Strunz 10th (pending) edition ID:7.DG.15

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
D : Sulfates (selenates, etc.) with additional anions, with H2O
G : With large and medium-sized cations; with NO3, CO3, B(OH)4, SiO4 or IO3
Dana 8th edition ID:32.4.4.2

32 : COMPOUND SULFATES
4 : Hydrated Compound Sulfates containing Hydroxyl or Halogen
Hey's CIM Ref.:25.11.23

25 : Sulphates
11 : Sulphates of Fe and other metals
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Type Occurrence of Sturmanite

Type Locality:Black Rock Mine, Black Rock, Kalahari manganese fields, Northern Cape Province, South Africa

Occurrences of Sturmanite

Geological Setting:Secondary mineral in cavities in metamorphosed manganese deposits.

Physical Properties of Sturmanite

Lustre:Vitreous, Greasy
Diaphaneity (Transparency):Transparent, Translucent
Comment:Greasy on fracture surfaces.
Colour:Bright Yellow to amber
Streak:Pale yellow, greenish yellow, brownish orange (altered)
Hardness (Mohs):2½
Tenacity:Brittle
Cleavage:Perfect
{1010}
Density (measured):1.847 g/cm3
Density (calculated):1.855 g/cm3

Crystallography of Sturmanite

Crystal System:Trigonal
Class (H-M):3m - Ditrigonal Pyramidal
Space Group:P3 1c
Cell Parameters:a = 11.16(3) Å, c = 21.79(9) Å
Ratio:a:c = 1 : 1.953
Unit Cell Volume:V 2,350.26 ų (Calculated from Unit Cell)
Z:2
Morphology:Dipyramidal tabular to elongated hexagonal crystals
Twinning:Probably

Optical Data of Sturmanite

Type:Uniaxial (+/-)
RI values: nω = 1.499 - 1.500 nε = 1.497 - 1.505
Maximum Birefringence:δ = 0.002

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Low
Pleochroism:Weak
Comments:O= pale green
E= pale yellowish green

Chemical Properties of Sturmanite

Formula:
Ca
 
6
(Fe
3+
 
,Al,Mn
3+
 
)
 
2
[(OH)
 
12
|B(OH)
 
4
|(SO
 
4
)
 
2
] · 25H
 
2
O
Essential elements:B, Ca, Fe, H, O, S
All elements listed in formula:Al, B, Ca, Fe, H, Mn, O, S

Relationship of Sturmanite to other Species

Related Minerals - Nickel-Strunz Grouping):
7.DG.05Darapskite
Na
 
3
NO
 
3
SO
 
4
·H
 
2
O
7.DG.10Clinoungemachite
(Na, K, Fe, SO
 
4
)
7.DG.10Humberstonite
Na
 
7
K
 
3
Mg
 
2
(SO
 
4
)
 
6
(NO
 
3
)
 
2
·6H
 
2
O
7.DG.10Ungemachite
K
 
3
Na
 
8
Fe(SO
 
4
)
 
6
(NO
 
3
)
 
2
·6H
 
2
O
7.DG.15Bentorite
Ca
 
6
(Cr
3+
 
,Al)
 
2
[(OH)
 
4
|SO
 
4
]
 
3
 · 26H
 
2
O
7.DG.15Charlesite
Ca
 
6
(Al,Si)
 
2
[(OH,O)
 
12
|B(OH)
 
4
|(SO
 
4
)
 
2
] · 26H
 
2
O
7.DG.15Ettringite
Ca
 
6
Al
 
2
[(OH)
 
4
|SO
 
4
]
 
3
 · 26H
 
2
O
7.DG.15Jouravskite
Ca
 
6
Mn
3+
2
[(OH)
 
4
|(SO
 
4
,CO
 
3
)]
 
3
 · 26H
 
2
O
7.DG.15Thaumasite
Ca
 
3
[CO
 
3
|SO
 
4
|Si(OH)
 
6
] · 12H
 
2
O
7.DG.15Carraraite
Ca
 
3
Ge(OH)
 
6
(SO
 
4
)(CO
 
3
)·12H
 
2
O
7.DG.15Buryatite
Ca
 
3
(Si,Fe,Al)[SO
 
4
][B(OH)
 
4
](OH)
 
5
O•
 
12
H
 
2
O
7.DG.15Korkinoite
7.DG.20Rapidcreekite
Ca
 
2
[CO
 
3
|SO
 
4
] · 4H
 
2
O
7.DG.25Tatarskite
Ca
 
6
Mg
 
2
(SO
 
4
)
 
2
(CO
 
3
)
 
2
Cl
 
4
(OH)
 
4
·7H
 
2
O
7.DG.25Chelyabinskite
(Ca,Mg)
 
3
[(SO
 
4
,CO
 
3
)
 
2
|Si(OH)
 
6
] · 9H
 
2
O (?)
7.DG.30Nakauriite
Cu
 
8
[(OH)
 
6
|CO
 
3
|(SO
 
4
)
 
4
] · 48H
 
2
O
7.DG.35Chessexite
(Na,K)
 
4
Ca
 
2
(Mg,Zn)
 
3
Al
 
8
[(SO
 
4
)
 
10
|(SiO
 
4
)
 
2
] · 40H
 
2
O
7.DG.40Carlosruizite
K
 
6
(Na,K)
 
4
Na
 
6
Mg
 
10
(SeO
 
4
)
 
12
(IO
 
3
)
 
12
·12H
 
2
O
7.DG.40Fuenzalidaite
K
 
6
(Na,K)
 
4
Na
 
6
Mg
 
10
(SO
 
4
)
 
12
(IO
 
3
)
 
12
·12H
 
2
O
Related Minerals - Hey's Index Grouping:
25.11.1Natrojarosite
NaFe
 
3
[(OH)
 
3
|SO
 
4
]
 
2
25.11.2Sideronatrite
Na
 
2
Fe(SO
 
4
)
 
2
OH·3H
 
2
O
25.11.3Metasideronatrite
Na
 
4
Fe
 
2
(SO
 
4
)
 
4
(OH)
 
2
·2H
 
2
O
25.11.4Ferrinatrite
Na
 
3
Fe(SO
 
4
)
 
3
·3H
 
2
O
25.11.5Amarillite
NaFe(SO
 
4
)
 
2
·6H
 
2
O
25.11.6Yavapaiite
KFe(SO
 
4
)
 
2
25.11.7Krausite
KFe(SO
 
4
)
 
2
·H
 
2
O
25.11.8Goldichite
KFe(SO
 
4
)
 
2
·4H
 
2
O
25.11.9Jarosite
KFe
3+
 
 
3
[(OH)
 
3
|SO
 
4
]
 
2
25.11.10Voltaite
K
 
2
Fe
2+
5
Fe
3+
3
Al[SO
 
4
]
 
12
 · 18H
 
2
O
25.11.11Ungemachite
K
 
3
Na
 
8
Fe(SO
 
4
)
 
6
(NO
 
3
)
 
2
·6H
 
2
O
25.11.12Metavoltine
Na
 
6
K
 
2
FeFe
 
6
(SO
 
4
)
 
12
O
 
2
·18H
 
2
O
25.11.13Sabieite
NH
 
4
Fe(SO
 
4
)
 
2
25.11.14Ammoniojarosite
(NH
 
4
)Fe
3+
3
[(OH)
 
3
|SO
 
4
]
 
2
25.11.15Clairite
(NH
 
4
)
 
2
Fe
 
3
(SO
 
4
)
 
4
(OH)
 
3
·3H
 
2
O
25.11.16Mohrite
(NH
 
4
)
 
2
Fe(SO
 
4
)
 
2
·6H
 
2
O
25.11.17Lonecreekite
(NH
 
4
)Fe
3+
 
[SO
 
4
]
 
2
 · 12H
 
2
O
25.11.18Godovikovite
NH
 
4
(Al,Fe)(SO
 
4
)
 
2
25.11.19Botryogen
MgFe
3+
 
[OH|(SO
 
4
)
 
2
] · 7H
 
2
O
25.11.21Slavíkite
NaMg
 
2
Fe
 
5
(SO
 
4
)
 
7
(OH)
 
6
·33H
 
2
O
25.11.24Millosevichite
(Al,Fe)
 
2
(SO
 
4
)
 
3
25.11.25Aluminocopiapite
Al
 
2/3
Fe
3+
4
[OH|(SO
 
4
)
 
3
]
 
2
 · 20H
 
2
O
25.11.26Halotrichite
FeAl
 
2
(SO
 
4
)
 
4
·22H
 
2
O
25.11.27Idrizite
(Mg,Fe)(Al,Fe)
 
2
(SO
 
4
)
 
3
(OH)
 
2
·15H
 
2
O or near
25.11.28Lishizhenite
ZnFe
 
2
(SO
 
4
)
 
4
·14H
 
2
O
25.11.29Zincovoltaite
K
 
2
Zn
 
5
Fe
3+
3
Al[SO
 
4
]
 
12
 · 18H
 
2
O

Other Names for Sturmanite

Synonyms:
IMA1981-011
German names:
Sturmanit
Russian names:
Стурманит
Spanish names:
Sturmanita

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Sturmanite

Reference List:Minerals of South Africa

Canadian Mineralogist (1983): 21: 705-709.

American Mineralogist (1988): 73: 195.

Grew, E.S., and Anovitz, L.M. (1996) BORON: Mineralogy, Petrology and Geochemistry, second edition, as revised (2002).

Internet Links for Sturmanite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Sturmanite in the Natural History Museum (London) online catalogue
  • Sturmanite details from Handbook of Mineralogy (PDF)
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    Localities for Sturmanite

    Hide Locality List
    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Russia
     
    • Northern Caucasus Region
      • Kabardino-Balkarian Republic
        • Verkhnechegemskiy volcanic structure
    		A. E. Zadov data
    South Africa
     
    • Northern Cape Province
      • Kalahari manganese fields
        • Black Rock
    		Can.Min.(1983) 21, 705-709; Minerals of South Africa
        • Hotazel
    		[Von Bezing, K. L. et al. (1991) - The Kalahari manganese field : an update, Mineralogical Record, 22 (3), 279-302]
        • N'Chwaning Mines
    		No reference listed
    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.
    Mineral and/or Locality
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