Sturmanite
A valid IMA mineral species
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About Sturmanite
Formula:
Ca6Fe3+2(SO4)2.5[B(OH)4](OH)12 · 25H2O
Fe(III) may be replaced by Al and Mn(III).
Colour:
Bright yellow to amber
Lustre:
Vitreous, Greasy
Hardness:
2½
Specific Gravity:
1.847
Crystal System:
Trigonal
Member of:
Name:
Named in 1983 by Donald R. Peacor, Pete J. Dunn, and Marjorie Duggan in honor of Bozidar Darko Sturman (7 October 1937 – 27 March 2019), Croatian-Canadian mineralogist and former Associate Curator of Mineralogy, Royal Ontario Museum, Toronto, Ontario, for his contributions to systematic mineralogy, in particular his studies of phosphate minerals from the Yukon and his refinement of methods used in optical mineralogy.
Ettringite Group.
A possible Mn4+ analogue is here coded as Unnamed (possible Mn(IV) analogue of sturmanite).
A possible Mn4+ analogue is here coded as Unnamed (possible Mn(IV) analogue of sturmanite).
Unique Identifiers
Mindat ID:
3817
Long-form identifier:
mindat:1:1:3817:7
Similar Names
IMA Classification of Sturmanite
Approved
IMA Formula:
Ca6Fe3+2(S6+O4)2.5[B(OH)4](OH)12·25H2O
Approval year:
1981
First published:
1983
Classification of Sturmanite
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
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
32.4.4.2
32 : COMPOUND SULFATES
4 : Hydrated Compound Sulfates containing Hydroxyl or Halogen
32 : COMPOUND SULFATES
4 : Hydrated Compound Sulfates containing Hydroxyl or Halogen
25.11.23
25 : Sulphates
11 : Sulphates of Fe and other metals
25 : Sulphates
11 : Sulphates of Fe and other metals
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Strm | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Sturmanite
Vitreous, Greasy
Transparency:
Transparent, Translucent
Comment:
Greasy on fracture surfaces
Colour:
Bright yellow to amber
Streak:
Pale yellow, greenish yellow, brownish orange (altered)
Hardness:
2½ on Mohs scale
Tenacity:
Very brittle
Cleavage:
Perfect
{1010}
{1010}
Density:
1.847 g/cm3 (Measured) 1.855 g/cm3 (Calculated)
Comment:
Measured with heavy liquids and pycnometer.
Optical Data of Sturmanite
Type:
Uniaxial (+/-)
RI values:
nω = 1.499 - 1.5 nε = 1.497 - 1.505
Max. Birefringence:
δ = 0.002 - 0.005
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Moderate (negative)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Pleochroism:
Weak
Comments:
O= pale green
E= pale yellowish green
E= pale yellowish green
Chemistry of Sturmanite
Mindat Formula:
Ca6Fe3+2(SO4)2.5[B(OH)4](OH)12 · 25H2O
Fe(III) may be replaced by Al and Mn(III).
Fe(III) may be replaced by Al and Mn(III).
Element Weights:
Crystallography of Sturmanite
Crystal System:
Trigonal
Class (H-M):
3m - Ditrigonal Pyramidal
Space Group:
P31c
Cell Parameters:
a = 11.16(3) Å, c = 21.79(9) Å
Ratio:
a:c = 1 : 1.953
Unit Cell V:
2,350.26 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Dipyramidal tabular to elongated hexagonal crystals. Forms include {10.4} modified by {11.4}. Exhibits parallel growth, stacked parallel to {0001}.
Twinning:
Probably
Comment:
Pushcharovsky et al. (2004) give: a 11.188(9), c 21.91(7) Å, V 2375.1(5) Å3.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 9.67 Å | (100) |
| 5.58 Å | (70) |
| 3.89 Å | (70) |
| 2.582 Å | (60) |
| 2.774 Å | (50) |
| 2.215 Å | (50) |
| 2.161 Å | (40) |
Comments:
Kuruman district, South Africa. Data from the type description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 3b: Earth’s earliest hydrosphere | >4.45 |
| 13 : Hadean serpentinization | |
| High-? alteration and/or metamorphism | |
| 32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47b : [Sulfates and sulfites] | |
| 47c : [Carbonates, phosphates, borates, nitrates] | |
| 47d : [Arsenates, antimonates, selenates, bismuthinates] |
Geological Setting:
Secondary mineral in cavities in metamorphosed manganese deposits.
Type Occurrence of Sturmanite
General Appearance of Type Material:
Flattened hexagonal dipyramidal crystals.
Place of Conservation of Type Material:
National Museum of Natural History (Smithsonian), Washington, D.C., USA, 148261.
Royal Ontario Museum, Toronto, Ontario, Canada.
Royal Ontario Museum, Toronto, Ontario, Canada.
Geological Setting of Type Material:
Metamorphosed bedded manganese deposit.
Associated Minerals at Type Locality:
Synonyms of Sturmanite
Other Language Names for Sturmanite
Relationship of Sturmanite to other Species
Member of:
Other Members of Ettringite Group:
| Bentorite | Ca6Cr2(SO4)3(OH)12 · 26H2O | Trig. 3m : P31c |
| Buryatite | Ca3(Si,Fe3+,Al)(SO4)B(OH)4(OH,O)6 · 12H2O | Trig. 3m : P31c |
| Carraraite | Ca3(SO4)[Ge(OH)6](CO3) · 12H2O | Hex. |
| Charlesite | Ca6(Al,Si)2(SO4)2[B(OH)4](OH,O)12 · 26H2O | Trig. 3m : P31c |
| Chiyokoite | Ca3Si(CO3)[B(OH)4]O (OH)5 · 12H2O | Hex. 6 : P63 |
| Ettringite | Ca6Al2(SO4)3(OH)12 · 26H2O | Trig. 3m : P31c |
| Hielscherite | Ca3Si(SO4)(SO3)(OH)6 · 11H2O | Hex. 6 : P63 |
| Imayoshiite | Ca3Al(CO3)[B(OH)4](OH)6 · 12H2O | Hex. 6/mmm(6/m2/m2/m) : P63/mmc |
| Jouravskite | Ca3Mn4+(SO4)(CO3)(OH)6 · 12H2O | Hex. 6 : P63 |
| Kottenheimite | Ca 3Si(SO4)2(OH)6 · 12H2O | Hex. 6/m : P63/m |
| Micheelsenite | (Ca2Y)Al(PO3OH)(CO3)(OH)6 · 12H2O | Hex. 6 : P63 |
| Siwaqaite | Ca6Al2(CrO4)3(OH)12 · 26H2O | Trig. 3m : P31c |
| Tatarinovite | Ca3Al(SO4)[B(OH)4](OH)6 · 12H2O | Hex. 6 : P63 |
| Thaumasite | Ca3(SO4)[Si(OH)6](CO3) · 12H2O | Hex. 6 : P63 |
| 'UM2008-07-CO:AlBCaHSSi' | Ca6(Al,Si)2(CO3,SO4)2[B(OH)4](OH,O)12 · 26H2O | |
| 'Unnamed (possible Mn(IV) analogue of Sturmanite)' | Ca6Mn4+2(SO4)2[B(OH)4](OH)10O2 · nH2O |
Common Associates
Associations Based on Photo Data:
| 43 photos of Sturmanite associated with Calcite | CaCO3 |
| 32 photos of Sturmanite associated with Manganite | Mn3+O(OH) |
| 29 photos of Sturmanite associated with Ettringite | Ca6Al2(SO4)3(OH)12 · 26H2O |
| 22 photos of Sturmanite associated with Brucite | Mg(OH)2 |
| 13 photos of Sturmanite associated with Quartz | SiO2 |
| 10 photos of Sturmanite associated with Hematite | Fe2O3 |
| 9 photos of Sturmanite associated with Gaudefroyite | Ca4Mn3+2-3(BO3)3(CO3)(O,OH)3 |
| 7 photos of Sturmanite associated with Charlesite | Ca6(Al,Si)2(SO4)2[B(OH)4](OH,O)12 · 26H2O |
| 7 photos of Sturmanite associated with Andradite | Ca3Fe3+2(SiO4)3 |
| 7 photos of Sturmanite associated with Hausmannite | Mn2+Mn3+2O4 |
Related Minerals - Strunz-mindat Grouping
| 7.DG. | Mathesiusite | K5(UO2)4(SO4)4(VO5) · 4H2O |
| 7.DG.05 | Darapskite | Na3(SO4)(NO3) · H2O |
| 7.DG.10 | Clinoungemachite | (Na, K, Fe, SO4) |
| 7.DG.10 | Humberstonite | Na7K3Mg2(SO4)6(NO3)2 · 6H2O |
| 7.DG.10 | Ungemachite | K3Na8Fe(SO4)6(NO3)2 · 6H2O |
| 7.DG.15 | Chiyokoite | Ca3Si(CO3)[B(OH)4]O (OH)5 · 12H2O |
| 7.DG.15 | Kottenheimite | Ca 3Si(SO4)2(OH)6 · 12H2O |
| 7.DG.15 | Hielscherite | Ca3Si(SO4)(SO3)(OH)6 · 11H2O |
| 7.DG.15 | Jouravskite | Ca3Mn4+(SO4)(CO3)(OH)6 · 12H2O |
| 7.DG.15 | Thaumasite | Ca3(SO4)[Si(OH)6](CO3) · 12H2O |
| 7.DG.15 | Bentorite | Ca6Cr2(SO4)3(OH)12 · 26H2O |
| 7.DG.15 | Carraraite | Ca3(SO4)[Ge(OH)6](CO3) · 12H2O |
| 7.DG.15 | Ettringite | Ca6Al2(SO4)3(OH)12 · 26H2O |
| 7.DG.15 | Birunite | Ca18(SiO3)8.5(CO3)8.5SO4 · 15H2O(?) |
| 7.DG.15 | Siwaqaite | Ca6Al2(CrO4)3(OH)12 · 26H2O |
| 7.DG.15 | Buryatite | Ca3(Si,Fe3+,Al)(SO4)B(OH)4(OH,O)6 · 12H2O |
| 7.DG.15 | Charlesite | Ca6(Al,Si)2(SO4)2[B(OH)4](OH,O)12 · 26H2O |
| 7.DG.15 | Tatarinovite | Ca3Al(SO4)[B(OH)4](OH)6 · 12H2O |
| 7.DG.15 | Imayoshiite | Ca3Al(CO3)[B(OH)4](OH)6 · 12H2O |
| 7.DG.20 | Rapidcreekite | Ca2(SO4)(CO3) · 4H2O |
| 7.DG.25 | Tatarskite | Ca6Mg2(SO4)2(CO3)2(OH)4Cl4 · 7H2O |
| 7.DG.30 | Nakauriite | Cu8(SO4)4(CO3)(OH)6 · 48H2O |
| 7.DG.35 | Chessexite | (Na,K)4Ca2(Mg,Zn)3Al8(SO4)10(SiO4)2 · 40H2O |
| 7.DG.40 | Fuenzalidaite | K6(Na,K)4Na6Mg10(SO4)12(IO3)12 · 12H2O |
| 7.DG.40 | Carlosruizite | K6(Na,K)4Na6Mg10(SeO4)12(IO3)12 · 12H2O |
| 7.DG.45 | 'Chelyabinskite' | (Ca,Mg)3(SO4,CO3)2[Si(OH)6] · 9H2O (?) |
| 7.DG.55 | Ramazzoite | [Mg8Cu12(PO4)(CO3)4(OH)24(H2O)20][(H0.33SO4)3(H2O)36] |
| 7.DG.60 | Witzkeite | Na4K4Ca(NO3)2(SO4)4 · 2H2O |
Fluorescence of Sturmanite
Does not fluoresce
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Sturmanite
mindat.org URL:
https://www.mindat.org/min-3817.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Sturmanite
Reference List:
Peacor, D. R., Dunn, P. J., Duggan, M. (1983) Sturmanite, a ferric iron, boron analogue of ettringite. The Canadian Mineralogist, 21 (4) 705-709
Cairncross, B., Dixon, R. (1995) Minerals of South Africa. Geological Society of South Africa. p.1-290.pages 60-66 and 244-245
Antao, S. M., Duane, M. J., Hassan, I. (2002) DTA, TG, and XRD studies of sturmanite and ettringite. The Canadian Mineralogist, 40 (5). 1403-1409 doi:10.2113/gscanmin.40.5.1403
Localities for Sturmanite
Showing 7 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Russia | |
| A. E. Zadov data |
South Africa (TL) | |
| Peacor et al. (1983) +3 other references |
| |
| Cairncross et al. (1995) +1 other reference | |
| King (n.d.) | |
| Pohl et al. (1991) | |
| Frost et al. (2014) |
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N'Chwaning III Mine, N'Chwaning Mines, Joe Morolong Local Municipality, John Taolo Gaetsewe District Municipality, Northern Cape, South Africa