Woodallite
A valid IMA mineral species
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About Woodallite
Formula:
Mg6Cr2(OH)16Cl2 · 4H2O
Colour:
Purple to deep magenta.
Lustre:
Resinous, Waxy
Hardness:
1½ - 2
Specific Gravity:
2.062
Crystal System:
Trigonal
Member of:
Name:
Named in honor of Dr. Roy Woodall AO, FAA, FTSE, (3 November 1930, Subiaco Perth, Western Australia, Australia - died 14 February 2021). Roy was an eminent Australian geologist who was instrumental in the initiation and development of the nickel and aluminium industries in Western Australia.
Hydrotalcite Group.
May grade into chromium-bearing iowaite.
See also the visually similar stichtite.
May grade into chromium-bearing iowaite.
See also the visually similar stichtite.
Unique Identifiers
Mindat ID:
10319
Long-form identifier:
mindat:1:1:10319:0
Similar Names
| Wadalite | A valid IMA mineral species | (Ca,Mg)6(Al,Fe3+)4((Si,Al)O4)3O4Cl3 |
| Weddellite | A valid IMA mineral species - grandfathered | Ca(C2O4) · (2.5-x)H2O |
IMA Classification of Woodallite
Approved
IMA Formula:
Mg6Cr3+2(OH)16Cl2·4H2O
Approval year:
2000
Classification of Woodallite
4.FL.05
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
L : Hydroxides with H2O +- (OH); sheets of edge-sharing octahedra
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
L : Hydroxides with H2O +- (OH); sheets of edge-sharing octahedra
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 |
|---|---|---|
| Wod | 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 Woodallite
Resinous, Waxy
Transparency:
Transparent
Colour:
Purple to deep magenta.
Streak:
Pale pink to white
Hardness:
1½ - 2 on Mohs scale
Tenacity:
Flexible
Cleavage:
Perfect
Perfect {0001}
Perfect {0001}
Density:
2.062(5) g/cm3 (Measured) 2.023 g/cm3 (Calculated)
Optical Data of Woodallite
Type:
Uniaxial (-)
RI values:
nω = 1.555 nε = 1.535
Max. Birefringence:
δ = 0.020
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 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:
violet to pinkish lilac.
Chemistry of Woodallite
Mindat Formula:
Mg6Cr2(OH)16Cl2 · 4H2O
Element Weights:
Crystallography of Woodallite
Crystal System:
Trigonal
Class (H-M):
3m(32/m) - Hexagonal Scalenohedral
Space Group:
R3m
Cell Parameters:
a = 3.10124(8) Å, c = 23.6817(16) Å
Ratio:
a:c = 1 : 7.636
Unit Cell V:
197.25 ų (Calculated from Unit Cell)
Comment:
3R polytype
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) |
|---|---|---|---|---|---|---|---|
| 0019807 | Woodallite | Mills S J, Whitfield P S, Kampf A R, Wilson S A, Dipple G M, Raudsepp M, Favreau G (2012) Contribution to the crystallography of hydrotalcites: the crystal structures of woodallite and takovite Journal of Geosciences 58 273-279 | 2012 | Mount Keith Nickel Mine, Western Australia, Australia | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 8.0361 Å | (100) |
| 4.0205 Å | (48) |
| 2.0072 Å | (6) |
| 2.3488 Å | (5) |
| 2.6239 Å | (3) |
| 1.6977 Å | (2) |
| 1.5237 Å | (2) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47e : [Vanadates, chromates, manganates] | |
| 47g : [Halogen-bearing surface weathering minerals] |
Type Occurrence of Woodallite
General Appearance of Type Material:
As platelets, commonly curved or crenulated, to
100 μm
100 μm
Place of Conservation of Type Material:
: South Australian Museum, Adelaide (G25116), the Western Australian Museum, Perth (WAM M1.2000), and the Museum of Victoria, Melbourne (M46222), Australia.
Associated Minerals at Type Locality:
Synonyms of Woodallite
Other Language Names for Woodallite
Relationship of Woodallite to other Species
Member of:
Other Members of Hydrotalcite Group:
| Desautelsite | Mg6Mn3+2(OH)16[CO3] · 4H2O | Trig. 3m(32/m) |
| Droninoite | Ni6Fe3+2(OH)16Cl2 · 4H2O | Trig. 3m(32/m) : R3m |
| Hydrotalcite | Mg6Al2(CO3)(OH)16 · 4H2O | Trig. 3m(32/m) : R3m |
| Iowaite | Mg6Fe3+2(OH)16Cl2 · 4H2O | Trig. 3m(32/m) : R3m |
| Kaznakhtite | Ni6Co3+2(CO3)(OH)16 · 4H2O | Trig. 3 : R3 |
| Meixnerite | Mg6Al2(OH)16(OH)2 · 4H2O | Trig. 3m(32/m) : R3m |
| Pyroaurite | Mg6Fe3+2(OH)16[CO3] · 4H2O | Trig. 3m(32/m) : R3m |
| Reevesite | Ni6Fe3+2(OH)16(CO3) · 4H2O | Trig. 3m(32/m) : R3m |
| Stichtite | Mg6Cr3+2(OH)16[CO3] · 4H2O | Trig. 3m(32/m) : R3m |
| Takovite | Ni6Al2(OH)16[CO3] · 4H2O | Trig. 3m(32/m) : R3m |
| 'UM2002-02-COH:FeNi' | (Fe2+,Ni)6Fe3+2(CO3)(OH)16 · 4H2O |
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 4.FL. | Trébeurdenite | Fe2+2Fe3+4O2(OH)10CO3 · 3H2O |
| 4.FL. | Mariakrite | [Ca4Al2(OH)12(H2O)4][Fe2S4] |
| 4.FL.05 | Muskoxite | Mg7Fe4O13 · 10H2O |
| 4.FL.05 | Jamborite | Ni2+1-xCo3+x(OH)2-x(SO4)x · nH2O |
| 4.FL.05 | Mössbauerite | Fe3+6O4(OH)8[CO3] · 3H2O |
| 4.FL.05 | Meixnerite | Mg6Al2(OH)16(OH)2 · 4H2O |
| 4.FL.05 | Fougèrite | Fe2+4Fe3+2(OH)12[CO3] · 3H2O |
| 4.FL.05 | Dritsite | Li2Al4(OH)12Cl2 · 3H2O |
| 4.FL.05 | Rotemite | Ca4Cr2(OH)12Cl2 · 4H2O |
| 4.FL.05 | Iowaite | Mg6Fe3+2(OH)16Cl2 · 4H2O |
| 4.FL.10 | Hydrocalumite | Ca4Al2(OH)12(Cl,CO3,OH)2 · 4H2O |
| 4.FL.15 | Kuzelite | Ca4Al2(OH)12[SO4] · 6H2O |
| 4.FL.20 | Jianshuiite | (Mg,Mn,Ca)Mn3O7 · 3H2O |
| 4.FL.20 | Ernienickelite | NiMn3O7 · 3H2O |
| 4.FL.20 | Aurorite | Mn2+Mn4+3O7 · 3H2O |
| 4.FL.20 | Chalcophanite | ZnMn4+3O7 · 3H2O |
| 4.FL.25 | Woodruffite | Zn2+x/2(Mn4+1-xMn3+x)O2 · yH2O |
| 4.FL.30 | Asbolane | (Ni,Co)2-xMn4+(O,OH)4 · nH2O |
| 4.FL.30 va | 'Lampadite' | Cu, Mn, O, H |
| 4.FL.35 | Buserite | Na4Mn14O27 · 21H2O |
| 4.FL.40 | Takanelite | (Mn,Ca)Mn4O9 · H2O |
| 4.FL.40 | Ranciéite | (Ca,Mn2+)0.2(Mn4+,Mn3+)O2 · 0.6H2O |
| 4.FL.45 | Birnessite | (Na,Ca)0.5(Mn4+,Mn3+)2O4 · 1.5H2O |
| 4.FL.55 | Cianciulliite | Mn(Mg,Mn)2Zn2(OH)10 · 2-4H2O |
| 4.FL.60 | Jensenite | Cu3[TeO6] · 2H2O |
| 4.FL.65 | Leisingite | Cu2MgTe6+O6 · 6H2O |
| 4.FL.70 | Magnesiohongruiite-(Fe3+) | (Mg2Fe3+)Fe3+NbO7(OH) |
| 4.FL.70 | Akdalaite | Al10O14(OH)2 |
| 4.FL.75 | Cafetite | CaTi2O5 · H2O |
| 4.FL.80 | Mourite | UMo5O12(OH)10 |
| 4.FL.85 | Deloryite | Cu4(UO2)(MoO4)2(OH)6 |
| 4.FL.90 | Lagalyite | Ca2xMn1-xO2 · 1.5-2H2O |
| 4.FL.95 | 'Tunnerite' | |
| 4.FL.100 | Carbocalumite | Ca4Al2(OH)12(CO3) · 6H2O |
| 4.FL.100 | Mampsisite | Ca4Al2(CO3)(OH)12 · 5H2O |
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 Woodallite
mindat.org URL:
https://www.mindat.org/min-10319.html
Please feel free to link to this page.
Please feel free to link to this page.
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Mineral Dealers:
References for Woodallite
Reference List:
Grguric, B.A., Madsen, I.C., Pring, A. (2001) Woodallite, a new chromium analogue of iowaite from the Mount Keith nickel deposit, Western Australia. Mineralogical Magazine, 65 (3). 427-435 doi:10.1180/002646101300119501
Mills, S. J., Whitfield, P. S., Kampf, A. R., Wilson, S. A., Dipple, G. M., Raudsepp, M., Favreau, F. (2012) Contribution to the crystallography of hydrotalcites: the crystal structures of woodallite and takovite. Journal of GEOsciences, 57 (4) 273-279
Localities for Woodallite
Showing 4 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.
Australia | |
| Grguric et al. (2013) |
| Wilson et al. (2014) | |
| Grguric et al. (2001) +2 other references |
Russia | |
| Zhitova et al. (2020) |
Quick NavTopAbout WoodalliteUnique IdentifiersSimilar NamesIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesRelationshipsCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Mount Keith Open Pit, Mount Keith, Wiluna Shire, Western Australia, Australia