Benauite
A valid IMA mineral species
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About Benauite
Formula:
SrFe3+3(PO4)(PO3OH)(OH)6
May contain some S replacing P.
Colour:
Yellow to brown
Lustre:
Vitreous, Resinous
Hardness:
3½
Specific Gravity:
3.65
Crystal System:
Trigonal
Member of:
Name:
For Benau mountain ("Benauer Berg"), on the slopes of which the type locality - the Clara mine - is situated.
The Sr analogue of kintoreite. Also the phosphorus (fully phosphatian) analogue of arsenobenauite.
Probably forms a solid solution with the phosphate-sulphate end member slottaite.
Probably forms a solid solution with the phosphate-sulphate end member slottaite.
Unique Identifiers
Mindat ID:
622
Long-form identifier:
mindat:1:1:622:2
Similar Names
| Bineite | A rock subtype | |
| Binnite (of Des Cloizeaux) | A variety of Tennantite-(Zn) | Cu6[Cu4(Fe,Zn)2]As4S13 |
| Binnite (of Heusser) | A synonym of Sartorite | |
| Bunnoite | A valid IMA mineral species | Mn62+AlSi6O18(OH)3 |
IMA Classification of Benauite
Approved
Approval year:
1995
First published:
1996
Classification of Benauite
8.BL.10
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
L : With medium-sized and large cations, (OH, etc.):RO4 = 3:1
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
L : With medium-sized and large cations, (OH, etc.):RO4 = 3:1
Dana 7th ed.:
42.7.4.6
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 |
|---|---|---|
| Bnu | 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 Benauite
Vitreous, Resinous
Transparency:
Transparent, Translucent
Colour:
Yellow to brown
Streak:
Yellowish
Hardness:
3½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
on {0001}
on {0001}
Fracture:
Conchoidal
Density:
3.65 g/cm3 (Measured) 3.648 g/cm3 (Calculated)
Optical Data of Benauite
Type:
Uniaxial (-)
RI values:
nω = 1.872(5) nε = 1.862(5)
2V:
Measured: 20°
Max. Birefringence:
δ = 0.010
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:
Very High (positive)
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:
Visible
Comments:
E = nearly colorless, O = yellow
Comments:
Anomalously biaxial, with blue interference colors.
Chemistry of Benauite
Mindat Formula:
SrFe3+3(PO4)(PO3OH)(OH)6
May contain some S replacing P.
May contain some S replacing P.
Element Weights:
Common Impurities:
K,Ca,Ba,Pb,Cu,Zn,Al,As
Crystallography of Benauite
Crystal System:
Trigonal
Class (H-M):
3m(32/m) - Hexagonal Scalenohedral
Space Group:
R3m
Cell Parameters:
a = 7.28(2) Å, c = 16.85(4) Å
Ratio:
a:c = 1 : 2.315
Unit Cell V:
773.38 ų (Calculated from Unit Cell)
Z:
3
Morphology:
Poorly formed platy to scaly crystals to 1 mm, flattened on {0001}; radial aggregates.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.88 Å | (10) |
| 3.06 Å | (9) |
| 3.65 Å | (6) |
| 2.25 Å | (6) |
| 2.96 Å | (5) |
| 2.81 Å | (5) |
| 2.53 Å | (5) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 23 : Subaerial aqueous alteration by non-redox-sensitive fluids (see also #47) | |
| 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] | |
| 47c : [Carbonates, phosphates, borates, nitrates] |
Type Occurrence of Benauite
General Appearance of Type Material:
Yellow to brown radial aggregates, up to 3 mm in diameter, consisting of scaly crystals flattened on (0001) and >1 mm in length.
Place of Conservation of Type Material:
Institute for Mineralogy and Crystal Chemistry, University of Stuttgart, Stuttgart, Germany.
Museum of Victoria, Melbourne, Australia.
Museum of Victoria, Melbourne, Australia.
Associated Minerals at Type Locality:
Synonyms of Benauite
Other Language Names for Benauite
Relationship of Benauite to other Species
Member of:
Other Members of Plumbogummite Group:
| Arsenobenauite | SrFe3+3(AsO4)(AsO3OH)(OH)6 | Trig. 3m(32/m) : R3m |
| Crandallite | CaAl3(PO4)(PO3OH)(OH)6 | Trig. 3m(32/m) : R3m |
| Eylettersite | Th0.75Al3(PO4)2(OH)6 | Trig. 3m(32/m) : R3m |
| Florencite-(Ce) | CeAl3(PO4)2(OH)6 | Trig. 3m(32/m) : R3m |
| Florencite-(La) | LaAl3(PO4)2(OH)6 | Trig. 3m(32/m) : R3m |
| Florencite-(Nd) | NdAl3(PO4)2(OH)6 | Trig. 3m(32/m) : R3m |
| Florencite-(Sm) | SmAl3(PO4)2(OH)6 | Trig. 3m(32/m) : R3m |
| Galloplumbogummite | Pb(Ga,Al,Ge)3(PO4)2(OH)6 | Trig. 3m : R3m |
| Gorceixite | BaAl3(PO4)(PO3OH)(OH)6 | Mon. m : Bm |
| Goyazite | SrAl3(PO4)(PO3OH)(OH)6 | Trig. 3m(32/m) : R3m |
| Kintoreite | PbFe3(PO4)(PO3OH)(OH)6 | Trig. 3m(32/m) : R3m |
| 'Kintoreite-2c' | PbFe3+3(PO4)2(OH,H2O)6 | |
| Plumbogummite | PbAl3(PO4)(PO3OH)(OH)6 | Trig. 3m(32/m) : R3m |
| Springcreekite | BaV3+3(PO4)2(OH,H2O)6 | Trig. 3m(32/m) : R3m |
| 'UM2006-23-PO:AlBiCaFeH' | (Ca,Bi)(Fe,Al)3(PO4)(PO3OH)(OH)6 | |
| 'Unnamed (As-analogue of Zaïrite)' | (Bi,Pb)Fe3+3(AsO4)2(OH)6 | |
| Waylandite | BiAl3(PO4)2(OH)6 | Trig. 3m(32/m) : R3m |
| Zaïrite | BiFe3+3(PO4)2(OH)6 | Trig. 3m(32/m) : R3m |
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 8.BL. | Kiryuite | NaMnAl(PO4)F3 |
| 8.BL. | Metaheimite | PbCu2(AsO4)(OH)3 |
| 8.BL. | Graulichite-(La) | LaFe3+3(AsO4)2(OH)6 |
| 8.BL. | Cloudite | BaFe3+3(PO4)(SO4)(OH)6 |
| 8.BL. | Oberwolfachite | SrFe3+3(AsO4)(SO4)(OH)6 |
| 8.BL. | Arsenobenauite | SrFe3+3(AsO4)(AsO3OH)(OH)6 |
| 8.BL.05 | Gallobeudantite | PbGa3(AsO4)(SO4)(OH)6 |
| 8.BL.05 | Slottaite | SrFe3+3(PO4)(SO4)(OH)6 |
| 8.BL.05 | Corkite | PbFe3+3(PO4)(SO4)(OH)6 |
| 8.BL.05 | Hidalgoite | PbAl3(AsO4)(SO4)(OH)6 |
| 8.BL.05 | Hinsdalite | PbAl3(PO4)(SO4)(OH)6 |
| 8.BL.05 | 'UM2011-07-POSO:AlBaH' | BaAl3(PO4)(SO4)(OH)6 |
| 8.BL.05 | Kemmlitzite | SrAl3(AsO4)(SO4)(OH)6 |
| 8.BL.05 | Beudantite | PbFe3+3(AsO4)(SO4)(OH)6 |
| 8.BL.05 | Weilerite | BaAl3(AsO4)(SO4)(OH)6 |
| 8.BL.05 | Woodhouseite | CaAl3(PO4)(SO4)(OH)6 |
| 8.BL.05 | Svanbergite | SrAl3(PO4)(SO4)(OH)6 |
| 8.BL.10 | Segnitite | PbFe3+3AsO4(AsO3OH)(OH)6 |
| 8.BL.10 | Arsenogoyazite | SrAl3(AsO4)(AsO3OH)(OH)6 |
| 8.BL.10 | Arsenogorceixite | BaAl3(AsO4)(AsO3OH)(OH)6 |
| 8.BL.10 | Dussertite | BaFe3+3(AsO4)(AsO3OH)(OH)6 |
| 8.BL.10 | Galloplumbogummite | Pb(Ga,Al,Ge)3(PO4)2(OH)6 |
| 8.BL.10 | Stibiosegnitite | Pb(Fe3+2.5Sb5+0.5)(AsO4)2(OH)6 |
| 8.BL.10 va | 'Viséite' | |
| 8.BL.10 | Arsenocrandallite | CaAl3(AsO4)(AsO3OH)(OH)6 |
| 8.BL.10 | Philipsbornite | PbAl3(AsO4)(AsO3OH)(OH)6 |
| 8.BL.10 | Crandallite | CaAl3(PO4)(PO3OH)(OH)6 |
| 8.BL.10 | Springcreekite | BaV3+3(PO4)2(OH,H2O)6 |
| 8.BL.10 | Eylettersite | Th0.75Al3(PO4)2(OH)6 |
| 8.BL.10 | Kintoreite | PbFe3(PO4)(PO3OH)(OH)6 |
| 8.BL.10 | Plumbogummite | PbAl3(PO4)(PO3OH)(OH)6 |
| 8.BL.10 | Gorceixite | BaAl3(PO4)(PO3OH)(OH)6 |
| 8.BL.10 | Goyazite | SrAl3(PO4)(PO3OH)(OH)6 |
| 8.BL.13 | Florencite-(Ce) | CeAl3(PO4)2(OH)6 |
| 8.BL.13 | Florencite-(La) | LaAl3(PO4)2(OH)6 |
| 8.BL.13 | Florencite-(Nd) | NdAl3(PO4)2(OH)6 |
| 8.BL.13 | Zaïrite | BiFe3+3(PO4)2(OH)6 |
| 8.BL.13 | Arsenoflorencite-(La) | LaAl3(AsO4)2(OH)6 |
| 8.BL.13 | 'Arsenoflorencite-(Nd)' | NdAl3(AsO4)2(OH)6 |
| 8.BL.13 | 'Unnamed (As-analogue of Zaïrite)' | (Bi,Pb)Fe3+3(AsO4)2(OH)6 |
| 8.BL.13 | Arsenoflorencite-(Ce) | CeAl3(AsO4)2(OH)6 |
| 8.BL.13 | Graulichite-(Ce) | CeFe3+3(AsO4)2(OH)6 |
| 8.BL.13 | 'Arsenowaylandite' | BiAl3(AsO4)2(OH)6 |
| 8.BL.13 | Waylandite | BiAl3(PO4)2(OH)6 |
| 8.BL.13 | Florencite-(Sm) | SmAl3(PO4)2(OH)6 |
| 8.BL.15 | Viitaniemiite | Na(Ca,Mn2+)Al(PO4)(F,OH)3 |
| 8.BL.25 | Pattersonite | PbFe3+3(PO4)2(OH)5 · H2O |
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 Benauite
mindat.org URL:
https://www.mindat.org/min-622.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Benauite
Localities for Benauite
Showing 5 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.
DR Congo | |
| |
Germany (TL) | |
| Walenta et al. (1996) +1 other reference |
Madagascar | |
| Berger et al. (2014) |
Spain | |
| Calvo et al. (2011) |
Tunisia | |
| Somrani et al. (2025) |
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Clara Mine, Oberwolfach, Ortenaukreis, Freiburg Region, Baden-Württemberg, Germany