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Vauxite
A valid IMA mineral species - grandfathered
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About Vauxite
George Vaux, Jr.
Formula:
Fe2+Al2(PO4)2(OH)2 · 6H2O
Colour:
Sky-blue, dark blue; pale blue in transmitted light.
Lustre:
Vitreous
Hardness:
3½
Specific Gravity:
2.39 - 2.4
Crystal System:
Triclinic
Name:
Named in honor of George Vaux, Jr. (18 December 1863, Philadelphia, Pennsylvania, USA - 24 October 1927, Bryn Mawr, Pennsylvania, USA), attorney, photographer, and mineral collector of Bryn Mawr, Pennsylvania. He was nephew of mineral collector William S. Vaux (1811-1882). His collection, that reached about 10,000 specimens of 850 species, went to Bryn Mawr College after his death.
A secondary mineral derived from the alteration of apatite.
Compare also the higher hydrate paravauxite and its dimorph metavauxite.
Ferrivauxite is an oxidized equivalent of vauxite.
Compare also the higher hydrate paravauxite and its dimorph metavauxite.
Ferrivauxite is an oxidized equivalent of vauxite.
Unique Identifiers
Mindat ID:
4164
Long-form identifier:
mindat:1:1:4164:1
Similar Names
IMA Classification of Vauxite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Fe2+Al2(PO4)2(OH)2·6H2O
First published:
1922
Classification of Vauxite
8.DC.35
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
42.11.14.1
42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
11 : (AB)3(XO4)2Zq·xH2O
42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
11 : (AB)3(XO4)2Zq·xH2O
19.14.23
19 : Phosphates
14 : Phosphates of Fe and other metals
19 : Phosphates
14 : Phosphates 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 |
|---|---|---|
| Vx | 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 Vauxite
Vitreous
Transparency:
Transparent
Colour:
Sky-blue, dark blue; pale blue in transmitted light.
Streak:
White
Hardness:
3½ on Mohs scale
Tenacity:
Brittle
Cleavage:
None Observed
Density:
2.39 - 2.4 g/cm3 (Measured) 2.4 g/cm3 (Calculated)
Optical Data of Vauxite
Type:
Biaxial (+)
RI values:
nα = 1.551 nβ = 1.555 nγ = 1.562
2V:
Measured: 32°
Max. Birefringence:
δ = 0.011
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:
Low (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:
r > v weak
Pleochroism:
Strong
Comments:
X = Z = Colourless
Y = Blue
Y = Blue
Chemistry of Vauxite
Mindat Formula:
Fe2+Al2(PO4)2(OH)2 · 6H2O
Element Weights:
Crystallography of Vauxite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 9.142 Å, b = 11.599 Å, c = 6.158 Å
α = 98.29°, β = 91.93°, γ = 108.27°
α = 98.29°, β = 91.93°, γ = 108.27°
Ratio:
a:b:c = 0.788 : 1 : 0.531
Unit Cell V:
611.42 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Crystals tabular {010}, elongated [001] or [101]. May exhibit may forms, including {010}, {110}, {111}, {101}, {111}, {101}, and {140}. Forms radial to subparallel aggregates; nodular.
Twinning:
on {010}, twin and composition plane.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
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Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
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) |
|---|---|---|---|---|---|---|---|
| 0000176 | Vauxite | Baur W H, Rama Rao B (1968) The crystal structure and the chemical composition of vauxite American Mineralogist 53 1025-1033 |  | 1968 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 10.85 Å | (100) |
| 5.457 Å | (20) |
| 5.908 Å | (12) |
| 2.881 Å | (12) |
| 2.596 Å | (12) |
| 6.069 Å | (10) |
| 3.045 Å | (10) |
Comments:
Llallagua, Bolivia.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47c : [Carbonates, phosphates, borates, nitrates] |
Geological Setting:
Alteration of apatite.
Type Occurrence of Vauxite
Place of Conservation of Type Material:
U.S. National Museum of Natural History, Washington, D.C., USA: #97561, #103542.
Geological Setting of Type Material:
Hydrothermal tin veins.
Associated Minerals at Type Locality:
Other Language Names for Vauxite
Common Associates
Associations Based on Photo Data:
| 642 photos of Vauxite associated with Paravauxite | Fe2+Al2(PO4)2(OH)2 · 8H2O |
| 348 photos of Vauxite associated with Childrenite | Fe2+Al(PO4)(OH)2 · H2O |
| 193 photos of Vauxite associated with Metavauxite | Fe2+Al2(PO4)2(OH)2 · 8H2O |
| 101 photos of Vauxite associated with Sigloite | Fe3+Al2(PO4)2(OH)3 · 7H2O |
| 101 photos of Vauxite associated with Quartz | SiO2 |
| 78 photos of Vauxite associated with Wavellite | Al3(PO4)2(OH)3 · 5H2O |
| 29 photos of Vauxite associated with Pyrite | FeS2 |
| 20 photos of Vauxite associated with Franckeite | Fe2+(Pb,Sn2+)6Sn4+2Sb2S14 |
| 8 photos of Vauxite associated with Greenockite | CdS |
| 5 photos of Vauxite associated with Römerite | Fe2+Fe3+2(SO4)4 · 14H2O |
Related Minerals - Strunz-mindat Grouping
| 8.DC. | Ferroberaunite | Fe2+Fe3+5(PO4)4(OH)5 · 6H2O |
| 8.DC. |
Siglo Veinte Mine, Llallagua, Rafael Bustillo Province, Potosí, Bolivia