Ferroberaunite
A valid IMA mineral species
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About Ferroberaunite
Formula:
Fe2+Fe3+5(PO4)4(OH)5 · 6H2O
Colour:
Green; dark greenish-brown, green, grading to gray
Lustre:
Vitreous, Pearly
Hardness:
3 - 4
Specific Gravity:
2.94
Crystal System:
Monoclinic
Member of:
Name:
Beraunite was originally defined as a fully oxidised mineral, but was redefined by Fanfani and Zanazzi (1967), on the basis of a crystal structural analysis, as a mixed-valence iron phosphate and they left the original fully oxidized end-member unnamed. In essence, Fanfani and Zanazzi (1967) had discovered a new mineral species (ferroberaunite) but re-used a previous name. In the 19th century, both beraunite and eleonorite had been applied to the fully oxidized mineral. Eleonorite had been re-applied by the IMA to the oxidized end-member of the beraunite-eleonorite series. In the IMA 21-D redefinition the name beraunite, based on a restudy of the type material, was reapplied to the oxidised phase (Vrtiška et al., 2022) and the name ferroberaunite was created for the mixed-valence phase (Tvrdý et al., 2021).
The Fe2+ analogue of zincoberaunite and beraunite.
Beraunite is now defined as Fe3+ dominant as originally described, and its previous unoxidised formula was incorrect. The latter is shown to be identical with "eleonorite" (which is now discredited).
Note: beraunite is always reddish, while ferrobraunite is greenish.
May be confused with acicular dufrénite and natrodufrénite.
The heteropolyhedral framework of the structure is similar to that of beraunite, contains Fe(1-4)(O,OH,H2O)6 octahedra, isolated PO4 tetrahedra, and wide channels hosting water molecules.
Beraunite is now defined as Fe3+ dominant as originally described, and its previous unoxidised formula was incorrect. The latter is shown to be identical with "eleonorite" (which is now discredited).
Note: beraunite is always reddish, while ferrobraunite is greenish.
May be confused with acicular dufrénite and natrodufrénite.
The heteropolyhedral framework of the structure is similar to that of beraunite, contains Fe(1-4)(O,OH,H2O)6 octahedra, isolated PO4 tetrahedra, and wide channels hosting water molecules.
Unique Identifiers
Mindat ID:
55602
Long-form identifier:
mindat:1:1:55602:8
IMA Classification of Ferroberaunite
Approved
IMA Formula:
Fe2+Fe3+5(PO4)4(OH)5·6H2O
Approval year:
2021
Approval history:
IMA No. 2021-036
beraunite redefinition (and eleonorite discreditation): IMA 21-D
beraunite redefinition (and eleonorite discreditation): IMA 21-D
Classification of Ferroberaunite
8.DC.
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
C : With only medium-sized cations, (OH, etc.):RO4 = 1:1 and < 2:1
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
C : With only medium-sized cations, (OH, etc.):RO4 = 1:1 and < 2:1
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 |
|---|---|---|
| Fbru | 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 Ferroberaunite
Vitreous, Pearly
Transparency:
Transparent, Translucent
Comment:
pearly on cleavages
Colour:
Green; dark greenish-brown, green, grading to gray
Streak:
Pale olive-green
Hardness:
3 - 4 on Mohs scale
Tenacity:
Brittle
Cleavage:
Very Good
parallel to {100}
parallel to {100}
Fracture:
Irregular/Uneven
Density:
2.94(2) g/cm3 (Measured) 2.907 g/cm3 (Calculated)
Optical Data of Ferroberaunite
Type:
Biaxial (-)
RI values:
nα = 1.736(2) nβ = 1.765(3) nγ = 1.786(5)
2V:
Measured: 68° (3), Calculated: 79°
Max. Birefringence:
δ = 0.050
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 biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
strong, r > v; orientation is Y = b; X ≈ a, Z ≈ c.
Pleochroism:
Strong
Comments:
X = bluish-green >> Z = green > Y = yellow
Chemistry of Ferroberaunite
Mindat Formula:
Fe2+Fe3+5(PO4)4(OH)5 · 6H2O
Element Weights:
Elements listed:
Crystallography of Ferroberaunite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/b
Setting:
C2/c
Cell Parameters:
a = 20.8708(3) Å, b = 5.1590(8) Å, c = 19.2263(3) Å
β = 93.3186(17)°
β = 93.3186(17)°
Ratio:
a:b:c = 4.046 : 1 : 3.727
Unit Cell V:
2,066.67 ų (Calculated from Unit Cell)
Z:
4
Twinning:
twinning is on {100}
Comment:
Greenish black "beraunite" (probably ferroberaunite) has: a = 20.953(8), b = 5.171(1), c = 19.266(4) Å, β = 93.34°.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 10.410 Å | (100) |
| 9.606 Å | (14) |
| 7.271 Å | (11) |
| 5.203 Å | (4) |
| 3.467 Å | (12) |
| 3.325 Å | (6) |
| 3.201 Å | (6) |
| 2.600 Å | (4) |
Type Occurrence of Ferroberaunite
General Appearance of Type Material:
flattened prismatic crystals up to 400 μm long
Place of Conservation of Type Material:
mineralogical collections of the Department of Mineralogy and Petrology, National Museum in Prague, Cirkusová 1740, Praha 9, Czech Republic, catalogue no. P1P 11/2021
Geological Setting of Type Material:
iron mine
Associated Minerals at Type Locality:
Synonyms of Ferroberaunite
Other Language Names for Ferroberaunite
Dutch:Ferroberauniet
German:Ferroberaunit
Relationship of Ferroberaunite to other Species
Member of:
Other Members of Beraunite Group:
| Beraunite | Fe3+6(PO4)4O(OH)4 · 6H2O | Mon. m : Bb |
| Tvrdýite | Fe2+Fe3+2Al3(PO4)4(OH)5(H2O)4 · 2H2O | Mon. 2/m : B2/b |
| Zincoberaunite | ZnFe3+5(PO4)4(OH)5 · 6H2O | Mon. 2/m : B2/b |
Common Associates
Associations Based on Photo Data:
| 34 photos of Ferroberaunite associated with Strengite | FePO4 · 2H2O |
| 16 photos of Ferroberaunite associated with Ferristrunzite | Fe3+Fe3+2(PO4)2(OH)3 · 5H2O |
| 13 photos of Ferroberaunite associated with Beraunite | Fe3+6(PO4)4O(OH)4 · 6H2O |
| 10 photos of Ferroberaunite associated with Strunzite | Mn2+Fe3+2(PO4)2(OH)2 · 6H2O |
| 9 photos of Ferroberaunite associated with Rockbridgeite | (Fe2+0.5Fe3+0.5)2Fe3+3(PO4)3(OH)5 |
| 6 photos of Ferroberaunite associated with Mitridatite | Ca2Fe3+3(PO4)3O2 · 3H2O |
| 6 photos of Ferroberaunite associated with Cacoxenite | Fe3+24AlO6(PO4)17(OH)12 · 75H2O |
| 6 photos of Ferroberaunite associated with Stewartite | Mn2+Fe3+2(PO4)2(OH)2 · 8H2O |
| 4 photos of Ferroberaunite associated with Goethite | Fe3+O(OH) |
| 4 photos of Ferroberaunite associated with Kummerite | Mn2+Fe3+Al(PO4)2(OH)2 · 8H2O |
Related Minerals - Strunz-mindat Grouping
| 8.DC. | Césarferreiraite | Fe2+ Fe3+2(AsO4)2(OH)2 · 8H2O |
| 8.DC. | Ferrivauxite | Fe3+Al2(PO4)2(OH)3 · 5H2O |
| 8.DC. | Ianbruceite | Zn2(AsO4)(OH) · 3H2O |
| 8.DC.05 | Nissonite | Cu2Mg2(PO4)2(OH)2 · 5H2O |
| 8.DC.07 | Euchroite | Cu2(AsO4)(OH) · 3H2O |
| 8.DC.10 | Legrandite | Zn2(AsO4)(OH) · H2O |
| 8.DC.12 | Strashimirite | Cu8(AsO4)4(OH)4 · 5H2O |
| 8.DC.15 | Earlshannonite | Mn2+Fe3+2(PO4)2(OH)2 · 4H2O |
| 8.DC.15 | Kunatite | CuFe3+2(PO4)2(OH)2 · 4H2O |
| 8.DC.15 | 'UM2006-27-PO:FeHZn' | ZnFe3+2(PO4)2(OH)2 · 4H2O |
| 8.DC.15 | 'UKI-2006-(PO:AlCuFeH)' | Fe2+Al3+2(PO4)2(OH)2 · 4H2O |
| 8.DC.15 | Cobaltarthurite | CoFe3+2(AsO4)2(OH)2 · 4H2O |
| 8.DC.15 | Arthurite | CuFe3+2(AsO4)2(OH)2 · 4H2O |
| 8.DC.15 | Ojuelaite | ZnFe3+2(AsO4)2(OH)2 · 4H2O |
| 8.DC.15 | Whitmoreite | Fe2+Fe3+2(PO4)2(OH)2 · 4H2O |
| 8.DC.15 | Bendadaite | Fe2+Fe3+2(AsO4)2(OH)2 · 4H2O |
| 8.DC.17 | Kleemanite | ZnAl2(PO4)2(OH)2 · 3H2O |
| 8.DC.20 | Magnesiobermanite | MgMn3+2(PO4)2(OH)2 · 4H2O |
| 8.DC.20 | Bermanite | Mn2+Mn3+2(PO4)2(OH)2 · 4H2O |
| 8.DC.20 | Coralloite | Mn2+Mn3+2(AsO4)2(OH)2 · 4H2O |
| 8.DC.22 | Kovdorskite | Mg2(PO4)(OH) · 3H2O |
| 8.DC.25 | Zincostrunzite | ZnFe3+2(PO4)2(OH)2 · 6.5H2O |
| 8.DC.25 | Metavauxite | Fe2+Al2(PO4)2(OH)2 · 8H2O |
| 8.DC.25 | Metavivianite | Fe2+Fe3+2(PO4)2(OH)2 · 6H2O |
| 8.DC.25 | Ferristrunzite | Fe3+Fe3+2(PO4)2(OH)3 · 5H2O |
| 8.DC.25 | Strunzite | Mn2+Fe3+2(PO4)2(OH)2 · 6H2O |
| 8.DC.25 | Ferrostrunzite | Fe2+Fe3+2(PO4)2(OH)2 · 6H2O |
| 8.DC.27 | Beraunite | Fe3+6(PO4)4O(OH)4 · 6H2O |
| 8.DC.27 | Tvrdýite | Fe2+Fe3+2Al3(PO4)4(OH)5(H2O)4 · 2H2O |
| 8.DC.27 | Zincoberaunite | ZnFe3+5(PO4)4(OH)5 · 6H2O |
| 8.DC.30 | Maghrebite | MgAl2(AsO4)2(OH)2 · 8H2O |
| 8.DC.30 | Ferrolaueite | Fe2+Fe3+2(PO4)2(OH)2 · 8H2O |
| 8.DC.30 | Ushkovite | MgFe3+2(PO4)2(OH)2 · 8H2O |
| 8.DC.30 | Laueite | Mn2+Fe3+2(PO4)2(OH)2 · 8H2O |
| 8.DC.30 | Paravauxite | Fe2+Al2(PO4)2(OH)2 · 8H2O |
| 8.DC.30 | Sigloite | Fe3+Al2(PO4)2(OH)3 · 7H2O |
| 8.DC.30 | Nordgauite | MnAl2(PO4)2(F,OH)2 · 5H2O |
| 8.DC.30 | Kayrobertsonite | [MnAl2(PO4)2(OH)2(H2O)4] · 2H2O |
| 8.DC.30 | Kummerite | Mn2+Fe3+Al(PO4)2(OH)2 · 8H2O |
| 8.DC.30 | Mangangordonite | Mn2+Al2(PO4)2(OH)2 · 8H2O |
| 8.DC.30 | Stewartite | Mn2+Fe3+2(PO4)2(OH)2 · 8H2O |
| 8.DC.30 | Gordonite | MgAl2(PO4)2(OH)2 · 8H2O |
| 8.DC.30 | Kastningite | (Mn2+,Fe2+,Mg)Al2(PO4)2(OH)2 · 8H2O |
| 8.DC.30 | Pseudolaueite | Mn2+Fe3+2(PO4)2(OH)2 · 8H2O |
| 8.DC.32 | Kamarizaite | Fe3+3(AsO4)2(OH)3 · 3H2O |
| 8.DC.32 | Tinticite | Fe3+3(PO4)2(OH)3 · 3H2O |
| 8.DC.35 | Vauxite | Fe2+Al2(PO4)2(OH)2 · 6H2O |
| 8.DC.37 | Vantasselite | Al4(PO4)3(OH)3 · 9H2O |
| 8.DC.40 | Cacoxenite | Fe3+24AlO6(PO4)17(OH)12 · 75H2O |
| 8.DC.45 | Souzalite | Mg3Al4(PO4)4(OH)6 · 2H2O |
| 8.DC.45 | Gormanite | (Fe2+,Mg)3(Al,Fe3+)4(PO4)4(OH)6 · 2H2O |
| 8.DC.47 | Kingite | Al3(PO4)2F2(OH) · 7H2O |
| 8.DC.50 | Allanpringite | Fe3+3(PO4)2(OH)3 · 5H2O |
| 8.DC.50 | Fluorwavellite | Al3(PO4)2(OH)2F · 5H2O |
| 8.DC.50 | Wavellite | Al3(PO4)2(OH)3 · 5H2O |
| 8.DC.52 | Kribergite | Al5(PO4)3(SO4)(OH)4 · 4H2O |
| 8.DC.55 | Mapimite | Zn2Fe3+3(AsO4)3(OH)4 · 10H2O |
| 8.DC.57 | Ogdensburgite | Ca2Fe3+4(Zn,Mn2+)(AsO4)4(OH)6 · 6H2O |
| 8.DC.60 | Cloncurryite | Cu0.5(VO)0.5Al2(PO4)2F2 · 5H2O |
| 8.DC.60 | Nevadaite | (Cu2+,Al,V3+)6Al8(PO4)8F8(OH)2 · 22H2O |
| 8.DC.62 | Kenngottite | Mn2+3Fe3+4(PO4)4(OH)6(H2O)2 |
| 8.DC.67 | Molinelloite | Cu(H2O)(OH)V4+O(V5+O4) |
| 8.DC.70 | Whitecapsite | H16Fe2+5Fe3+14Sb3+6(AsO4)18O16 · 120H2O |
| 8.DC.75 | Heimite | PbCu2(AsO4)(OH)3 · 2H2O |
| 8.DC.80 | Lednevite | Cu[PO3(OH)] · H2O |
Other Information
Notes:
Ferroberaunite dissolves easily in HCl (35%), slowly in H3PO4 (85%); it does not dissolve in HNO3
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 Ferroberaunite
mindat.org URL:
https://www.mindat.org/min-55602.html
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References for Ferroberaunite
Reference List:
Larsen, Esper S. (1921) The microscopic determination of the nonopaque minerals. Bulletin 679. US Geological Survey doi:10.3133/b679 p.46
Fanfani, I., Zanazzi, P. F. (1967) The crystal structure of beraunite. Acta Crystallographica, 22 (2) 173-181 doi:10.1107/s0365110x67000301
Moore, Paul B. (1970) Crystal chemistry of the basic iron phosphates. American Mineralogist, 55 (1-2) 135-169
Moore, Paul B., Kampf, Anthony R. (1992) Beraunite: Refinement, comparative crystal chemistry, and selected bond valences. Zeitschrift für Kristallographie, 201 (3-4). 263-281 doi:10.1524/zkri.1992.201.3-4.263
Chukanov, Nikita V., Aksenov, Sergey M., Rastsvetaeva, Ramiza K., Schäfer, Christof, Pekov, Igor V., Belakovskiy, Dmitriy I., Scholz, Ricardo, de Oliveira, Luiz C.A., Britvin, Sergey N. (2017) Eleonorite, Fe63+(PO4)4O(OH)4·6H2O: validation as a mineral species and new data. Mineralogical Magazine, 81 (1) 61-76 doi:10.1180/minmag.2016.080.070
Miyawaki, Ritsuro, Hatert, Frédéric, Pasero, Marco, Mills, Stuart J. (2021) IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) CNMNC Newsletter No 63. Mineralogical Magazine, 85 (6) 910-915 doi:10.1180/mgm.2021.74
Vrtiška, Luboš, Tvrdý, Jaromír, Plášil, Jakub, Sejkora, Jiří, Škoda, Radek, Chukanov, Nikita V., Massanek, Andreas, Filip, Jan, Dolníček, Zdeněk, Veselovský, František (2022) Redefinition of beraunite, Fe3+6(PO4)4O(OH)4⋅6H2O, and discreditation of the name eleonorite: a re-investigation of type material from the Hrbek Mine (Czech Republic) European Journal of Mineralogy, 34 (2) 223-238 doi:10.5194/ejm-34-223-2022
Tvrdý, Jaromír, Plášil, Jakub, Vrtiška, Luboš, Sejkora, Jiří, Škoda, Radek, Dolníček, Zdeněk, Petr, Martin, Veselovský, František (2022) Ferroberaunite, Fe2+Fe3+5(PO4)4(OH)5⋅6H2O, a mixed-valence iron member of the beraunite series, from the Gravel Hill mine, Perranzabuloe, Cornwall, England. Mineralogical Magazine, 86 (3) 363-372 doi:10.1180/mgm.2022.15
Localities for Ferroberaunite
Showing 32 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.
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Gravel Hill Mine, Perran Iron Lode, Perranzabuloe, Cornwall, England, UK