Sherwoodite
A valid IMA mineral species - grandfathered
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About Sherwoodite
Formula:
Ca5.5(AlV4+V5+12O39) · 28H2O
formerly given as Ca4.5(AlV4+2V5+12O40)·28H2O
Colour:
Dark bluish black (fresh), blue-green, yellow-green (altered)
Lustre:
Vitreous, Earthy
Hardness:
2
Specific Gravity:
2.8
Crystal System:
Tetragonal
Name:
For Alexander M. Sherwood (1888–1966?), an analytical chemist of the United States Geological Survey (USGS).
Type Locality:
This mineral contains aluminovanadate(IV,V) polyanions, consisting of 14 (VO6) octahedra condensed by edge-sharing around a central (AlO6) octahedron (Evans and Konnert, 1978).
The structure is based on [AlV4+V5+12O39]11− vanadoaluminate anion, as redefined in 2023.
The structure is based on [AlV4+V5+12O39]11− vanadoaluminate anion, as redefined in 2023.
Unique Identifiers
Mindat ID:
3637
Long-form identifier:
mindat:1:1:3637:1
IMA Classification of Sherwoodite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Ca4.5AlV4+2V5+12O40 · 28H2O
First published:
1958
Classification of Sherwoodite
4.HC.15
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
H : V[5,6] Vanadates
C : [6]-Sorovanadates
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
H : V[5,6] Vanadates
C : [6]-Sorovanadates
47.2.4.1
47 : VANADIUM OXYSALTS
2 : Anhydrous Vanadium Oxysalts Containing Hydroxyl or Halogen
47 : VANADIUM OXYSALTS
2 : Anhydrous Vanadium Oxysalts Containing Hydroxyl or Halogen
21.2.9
21 : Vanadates (and vanadates with arsenate or phosphate)
2 : Vanadates of Mg, Ca, Sr or Ba
21 : Vanadates (and vanadates with arsenate or phosphate)
2 : Vanadates of Mg, Ca, Sr or Ba
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 |
|---|---|---|
| Swd | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Sherwoodite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Sherwoodite
Vitreous, Earthy
Transparency:
Translucent
Colour:
Dark bluish black (fresh), blue-green, yellow-green (altered)
Streak:
Pale blue.
Hardness:
2 on Mohs scale
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
2.8(1) g/cm3 (Measured) 2.56 g/cm3 (Calculated)
Optical Data of Sherwoodite
Type:
Uniaxial (-)
RI values:
nω = 1.765(3) nε = 1.735 - 1.738
Max. Birefringence:
δ = 0.027 - 0.030
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.
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.
Surface Relief:
Moderate
Pleochroism:
Visible
Comments:
O = green to yellow-brown; E = blue to deep blue-green.
Chemistry of Sherwoodite
Mindat Formula:
Ca5.5(AlV4+V5+12O39) · 28H2O
formerly given as Ca4.5(AlV4+2V5+12O40)·28H2O
formerly given as Ca4.5(AlV4+2V5+12O40)·28H2O
Element Weights:
Chemical Analysis
Empirical formulas:
| Sample ID | Empirical Formula |
|---|---|
| 1 | (Ca4.26Mg1.09Na0.35K0.04Sr0.03)[Al0.87(V4+V5+12)O39]·28.15H2O |
Sample references:
| ID | Locality | Reference | Notes |
|---|---|---|---|
| 1 | Peanut Mine, Bull Canyon, Montrose County, Colorado, USA | Hughes, John M., Kampf, Anthony R., Nash, Barbara P., Marty, Joe (2023) The Atomic Arrangement of the Sherwoodite Structural Unit: Redefinition of the Sherwoodite Vanadoaluminate Heteropoly Complex as [AlV4+V5+12O39]11−. The Canadian Journal of Mineralogy and Petrology, 61 (5). 979-986 doi:10.3749/2300002 | empirical formula basis: 12 V atoms pfu; the locality is given in the abstract as "Uravan Mineral Belt" |
Crystallography of Sherwoodite
Crystal System:
Tetragonal
Class (H-M):
4/mmm(4/m2/m2/m) - Ditetragonal Dipyramidal
Space Group:
I41/amd
Setting:
I41/amd
Cell Parameters:
a = 27.9085(7) Å, c = 13.8090(5) Å
Ratio:
a:c = 1 : 0.495
Unit Cell V:
10,755.61 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Crystals are equant or slightly flattened. Type material crystals display only two forms: m{110} and d{011}.
Comment:
crystallizes as a structural variation of the putative (AlV4+,5+14O40)n− vanadoaluminate complex
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) |
|---|---|---|---|---|---|---|---|
| 0000685 | Sherwoodite | Evans H T, Konnert J A (1978) The crystal chemistry of sherwoodite, a calcium 14-vanadoaluminate heteropoly complex American Mineralogist 63 863-868 |  | 1978 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 12.3 Å | (strong) |
| 10.0 Å | (strong) |
| 9.3 Å | (moderately strong) |
| 2.61 Å | (moderate) |
| 2.10 Å | (moderate broad) |
| 7.8 Å | (weak) |
| 7.1 Å | (weak) |
Comments:
Colorado Plateau, USA. The data are from the type description.
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] | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 53 : Other minerals with taphonomic origins | <0.4 |
Geological Setting:
sandstone uranium deposits
Type Occurrence of Sherwoodite
General Appearance of Type Material:
Equant or slightly flattened crystals, occurring singly and as polycrystalline aggregates.
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA, 115883, 121951.
Geological Setting of Type Material:
Oxidation of vanadium minerals on fracture surfaces in sandstones and mineralized coalified wood.
Associated Minerals at Type Locality:
Other Language Names for Sherwoodite
Dutch:Sherwoodiet
German:Sherwoodit
Russian:Шервудит
Simplified Chinese:柱水钒钙矿
Spanish:Sherwoodita
Traditional Chinese:柱水釩鈣礦
Common Associates
Associations Based on Photo Data:
| 4 photos of Sherwoodite associated with Pascoite | Ca2Ca(V10O28) · 17H2O |
| 2 photos of Sherwoodite associated with Rossite | Ca(VO3)2 · 4H2O |
| 1 photo of Sherwoodite associated with Carnotite | K2(UO2)2(VO4)2 · 3H2O |
| 1 photo of Sherwoodite associated with Magnesiopascoite | Ca2Mg(V10O28) · 16H2O |
| 1 photo of Sherwoodite associated with Gypsum | CaSO4 · 2H2O |
Related Minerals - Strunz-mindat Grouping
| 4.HC. | Protocaseyite | [Al4(OH)6(H2O)12][V10O28] · 8H2O |
| 4.HC. | Ammoniolasalite | [(NH4)2Mg2(H2O)20] [V10O28] |
| 4.HC. | Beckettite | Ca2V6Al6O20 |
| 4.HC.05 | Pascoite | Ca2Ca(V10O28) · 17H2O |
| 4.HC.05 | Hydropascoite | Ca3(V10O28) · 24H2O |
| 4.HC.05 | Lasalite | Na2Mg2(V10O28) · 20H2O |
| 4.HC.05 | Hughesite | Na3Al(V10O28) · 22H2O |
| 4.HC.05 | Magnesiopascoite | Ca2Mg(V10O28) · 16H2O |
| 4.HC.05 | Rakovanite | (NH4)3Na3(V10O28) · 12H2O |
| 4.HC.10 | Hummerite | K2Mg2(V10O28) · 16H2O |
| 4.HC.20 | Bluestreakite | K4Mg2(V4+2V5+8O28) · 14H2O |
| 4.HC.25 | Wernerbaurite | {(NH4)2[Ca2(H2O)14](H2O)2}{V10O28} |
| 4.HC.25 | Burroite | Ca2(NH4)2(V10O28) · 15H2O |
| 4.HC.30 | Caseyite | [(V5+O2)Al10-x(OH)20-2x(H2O)18-2x]2[H2V4+V5+9O28][V5+10O28]2(Na,K,Ca)2-y(SO4)2-z · (60+8x+y+4z)H2O (x = 0-2.5; y = 0-2; z = 0-2) |
| 4.HC.35 | Gunterite | Na4Ca(V10O28) · 20H2O |
| 4.HC.40 | Kokinosite | Na2Ca2(V10O28) · 24H2O |
| 4.HC.45 | Nashite | Na3Ca2[(V5+9V4+)O28] · 24H2O |
| 4.HC.50 | Okieite | Mg3[V10O28] · 28H2O |
| 4.HC.55 | Postite | Mg(H2O)6Al2(OH)2(H2O)8(V10O28) · 13H2O |
| 4.HC.60 | Schindlerite | {(NH4)4Na2(H2O)10}{V10O28} |
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 Sherwoodite
mindat.org URL:
https://www.mindat.org/min-3637.html
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References for Sherwoodite
Reference List:
Thompson, Mary E., Roach, Carl H., Meyrowitz, Robert (1958) Sherwoodite, a mixed vanadium(IV)-vanadium (V) mineral from the Colorado Plateau. American Mineralogist, 43 (7-8) 749-755
Evans, Howard T. Jr., Konnert, Judith A. (1978) The crystal chemistry of sherwoodite, a calcium 14-vanadoaluminate heteropoly complex. American Mineralogist, 63 (9-10) 863-868
Hughes, John M., Kampf, Anthony R., Nash, Barbara P., Marty, Joe (2023) The Atomic Arrangement of the Sherwoodite Structural Unit: Redefinition of the Sherwoodite Vanadoaluminate Heteropoly Complex as [AlV4+V5+12O39]11−. The Canadian Journal of Mineralogy and Petrology, 61 (5). 979-986 doi:10.3749/2300002
Localities for Sherwoodite
Showing 28 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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Firefly–Pigmay Mine, La Sal Creek Mining District, San Juan County, Utah, USA