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Gaudefroyite
A valid IMA mineral species
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About Gaudefroyite
Christophe Gaudefroy
Formula:
Ca4Mn3+2-3(BO3)3(CO3)(O,OH)3
Colour:
Black
Lustre:
Vitreous, Dull
Hardness:
6
Specific Gravity:
3.35 - 3.50
Crystal System:
Hexagonal
Name:
Named in 1964 by Georges Jouravsky and François Permingeat in honor of Christophe-Léon Gaudefroy (1878, Beaucamps-le-Vieux, Somme, France - 1971), French ecclesiastic and mineralogist. He was the professor of mineralogy at the Catholic Institute of Paris for nearly 30 years and also worked at the Sorbonne. After that, he worked for the Geological Survey of Morocco.
Opaque, but transparent in thin slivers.
Unique Identifiers
Mindat ID:
1660
Long-form identifier:
mindat:1:1:1660:1
IMA Classification of Gaudefroyite
Approved
IMA Formula:
Ca4Mn3+3(BO3)3(CO3)O3
Approval year:
1964
First published:
1964
Classification of Gaudefroyite
6.AB.60
6 : BORATES
A : Monoborates
B : BO3, with additional anions; 1(D) + OH, etc.
6 : BORATES
A : Monoborates
B : BO3, with additional anions; 1(D) + OH, etc.
27.1.2.1
27 : COMPOUND BORATES
1 : Miscellaneous
27 : COMPOUND BORATES
1 : Miscellaneous
10.4.6
10 : Borates with other anions
4 : Borates with carbonate
10 : Borates with other anions
4 : Borates with carbonate
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 |
|---|---|---|
| Gfy | 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 Gaudefroyite
Vitreous, Dull
Transparency:
Opaque
Comment:
Vitreous to dull
Colour:
Black
Streak:
Brown
Hardness:
6 on Mohs scale
Hardness:
VHN100=840 - Vickers
Tenacity:
Brittle
Cleavage:
Distinct/Good
Prismatic {11.0)
Prismatic {11.0)
Fracture:
Conchoidal
Density:
3.35 - 3.50 g/cm3 (Measured) 3.49(5) g/cm3 (Calculated)
Optical Data of Gaudefroyite
Type:
Uniaxial (+)
RI values:
nω = 1.805 - 1.81 nε = 2.015 - 2.02
Max. Birefringence:
δ = 0.210
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.
Anisotropism:
Strong, in pale gray
Reflectivity:
| Wavelength | R1 (%) | R2 (%) |
|---|---|---|
| 400nm | 11.2% | 15.4% |
| 440nm | 10.4% | 14.2% |
| 480nm | 9.9% | 13.4% |
| 520nm | 9.6% | 12.8% |
| 560nm | 9.5% | 12.3% |
| 600nm | 9.4% | 12.1% |
| 640nm | 9.3% | 11.9% |
| 680nm | 9.3% | 11.7% |
| 700nm | 9.3% | 11.7% |
Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 15.4%.
R1 shown in black, R2 shown in red
Colour in reflected light:
Gray
Internal Reflections:
Strong yellow-orange to reddish
Pleochroism:
Strong
Comments:
O = pale yellowish brown; E = red-orange
Chemistry of Gaudefroyite
Mindat Formula:
Ca4Mn3+2-3(BO3)3(CO3)(O,OH)3
Element Weights:
Crystallography of Gaudefroyite
Crystal System:
Hexagonal
Cell Parameters:
a = 10.589(1) Å, c = 5.891(1) Å
Ratio:
a:c = 1 : 0.556
Unit Cell V:
572.04 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Hexagonal prisms with pyramidal terminations. (1010), (1120), (2021), (1121), (1011).
Twinning:
None observed in type material
Comment:
Point Group: 6 or 6m.; Space Group: P63 or disordered P63/m
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0006167 | Gaudefroyite | Antao S M, Hassan I (2008) Gaudefroyite, Ca8Mn3+6[(BO3)6(CO3)2O6]: high-temperature crystal structure The Canadian Mineralogist 46 183-193 |  | 2008 | Wessels mine, Kalahari manganese field, South Africa | 0 | 298 |
| 0006179 | Gaudefroyite | Antao S M, Hassan I (2008) Gaudefroyite, Ca8Mn3+6[(BO3)6(CO3)2O6]: high-temperature crystal structure The Canadian Mineralogist 46 183-193 | | 2008 | Wessels mine, Kalahari manganese field, South Africa | 0 | 293 |
| 0006178 | Gaudefroyite | Antao S M, Hassan I (2008) Gaudefroyite, Ca8Mn3+6[(BO3)6(CO3)2O6]: high-temperature crystal structure The Canadian Mineralogist 46 183-193 | | 2008 | Wessels mine, Kalahari manganese field, South Africa | 0 | 293 |
| 0006177 | Gaudefroyite | Antao S M, Hassan I (2008) Gaudefroyite, Ca8Mn3+6[(BO3)6(CO3)2O6]: high-temperature crystal structure The Canadian Mineralogist 46 183-193 | | 2008 | Wessels mine, Kalahari manganese field, South Africa | 0 | 293 |
| 0006176 | Gaudefroyite | Antao S M, Hassan I (2008) Gaudefroyite, Ca8Mn3+6[(BO3)6(CO3)2O6]: high-temperature crystal structure The Canadian Mineralogist 46 183-193 | | 2008 | Wessels mine, Kalahari manganese field, South Africa | 0 | 293 |
| 0006175 | Gaudefroyite | Antao S M, Hassan I (2008) Gaudefroyite, Ca8Mn3+6[(BO3)6(CO3)2O6]: high-temperature crystal structure The Canadian Mineralogist 46 183-193 | | 2008 | Wessels mine, Kalahari manganese field, South Africa | 0 | 293 |
| 0006174 | Gaudefroyite | Antao S M, Hassan I (2008) Gaudefroyite, Ca8Mn3+6[(BO3)6(CO3)2O6]: high-temperature crystal structure The Canadian Mineralogist 46 183-193 | | 2008 | Wessels mine, Kalahari manganese field, South Africa | 0 | 293 |
| 0006173 | Gaudefroyite | Antao S M, Hassan I (2008) Gaudefroyite, Ca8Mn3+6[(BO3)6(CO3)2O6]: high-temperature crystal structure The Canadian Mineralogist 46 183-193 | | 2008 | Wessels mine, Kalahari manganese field, South Africa | 0 | 293 |
| 0006172 | Gaudefroyite | Antao S M, Hassan I (2008) Gaudefroyite, Ca8Mn3+6[(BO3)6(CO3)2O6]: high-temperature crystal structure The Canadian Mineralogist 46 183-193 | | 2008 | Wessels mine, Kalahari manganese field, South Africa | 0 | 293 |
| 0006171 | Gaudefroyite | Antao S M, Hassan I (2008) Gaudefroyite, Ca8Mn3+6[(BO3)6(CO3)2O6]: high-temperature crystal structure The Canadian Mineralogist 46 183-193 | | 2008 | Wessels mine, Kalahari manganese field, South Africa | 0 | 293 |
| 0006170 | Gaudefroyite | Antao S M, Hassan I (2008) Gaudefroyite, Ca8Mn3+6[(BO3)6(CO3)2O6]: high-temperature crystal structure The Canadian Mineralogist 46 183-193 | | 2008 | Wessels mine, Kalahari manganese field, South Africa | 0 | 293 |
| 0006169 | Gaudefroyite | Antao S M, Hassan I (2008) Gaudefroyite, Ca8Mn3+6[(BO3)6(CO3)2O6]: high-temperature crystal structure The Canadian Mineralogist 46 183-193 | | 2008 | Wessels mine, Kalahari manganese field, South Africa | 0 | 293 |
| 0006168 | Gaudefroyite | Antao S M, Hassan I (2008) Gaudefroyite, Ca8Mn3+6[(BO3)6(CO3)2O6]: high-temperature crystal structure The Canadian Mineralogist 46 183-193 | | 2008 | Wessels mine, Kalahari manganese field, South Africa | 0 | 293 |
| 0006635 | Gaudefroyite | Hoffmann C, Armbruster T, Kunz M (1997) Structure refinement of (001) disordered gaudefroyite Ca4Mn3[(BO3)3(CO3)O3]: Jahn-Teller-distortion in edge-sharing chains of MnO6 octahedra European Journal of Mineralogy 9 7-19 | 1997 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Loading XRD data...
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.95 Å | (vs) |
| 2.62 Å | (vs) |
| 2.46 Å | (vs) |
| 9.1 Å | (s) |
| 4.54 Å | (s) |
| 2.69 Å | (s) |
| 1.80 Å | (s) |
| 4.89 Å | (m) |
| 2.31 Å | (m) |
| 2.23 Å | (m) |
| 1.91 Å | (m) |
| 1.49 Å | (m) |
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) |
Type Occurrence of Gaudefroyite
General Appearance of Type Material:
Acicular hexagonal prisms up to 5 cm long, with pyramidal terminations.
Place of Conservation of Type Material:
Geological Survey of Morocco, Rabat, Morocco.
Natural History Museum, Paris, France, 165.34.
National School of Mines, Paris, France.
Natural History Museum, Paris, France, 165.34.
National School of Mines, Paris, France.
Geological Setting of Type Material:
Hydrothermal mineral in manganese deposits
Associated Minerals at Type Locality:
Synonyms of Gaudefroyite
Other Language Names for Gaudefroyite
Dutch:Gaudefroyiet
German:Gaudefroyit
Russian:Годефруаит
Simplified Chinese:碳硼锰钙石
Spanish:Gaudefroyita
Traditional Chinese:碳硼錳鈣石
Common Associates
Associations Based on Photo Data:
| 130 photos of Gaudefroyite associated with Andradite | Ca3Fe3+2(SiO4)3 |
| 56 photos of Gaudefroyite associated with Hausmannite | Mn2+Mn3+2O4 |
| 48 photos of Gaudefroyite associated with Calcite | CaCO3 |
| 47 photos of Gaudefroyite associated with Baryte | BaSO4 |
| 33 photos of Gaudefroyite associated with Ettringite | Ca6Al2(SO4)3(OH)12 · 26H2O |
| 22 photos of Gaudefroyite associated with Hematite | Fe2O3 |
| 10 photos of Gaudefroyite associated with Oyelite | Ca10Si8B2O29 · 12.5H2O |
| 9 photos of Gaudefroyite associated with Sturmanite | Ca6Fe3+2(SO4)2.5[B(OH)4](OH)12 · 25H2O |
| 8 photos of Gaudefroyite associated with Manganite | Mn3+O(OH) |
| 6 photos of Gaudefroyite associated with Thaumasite | Ca3(SO4)[Si(OH)6](CO3) · 12H2O |
Related Minerals - Strunz-mindat Grouping
| 6.AB. | Chubarovite | KZn2(BO3)Cl2 |
| 6.AB. | Rhabdoborite-(Mo) | Mg12Mo6+1.33O6(BO3)6F2 |
| 6.AB.05 | Hambergite | Be2(BO3)(OH) |
| 6.AB.10 |
Wessels Mine, Joe Morolong Local Municipality, John Taolo Gaetsewe District Municipality, Northern Cape, South Africa