Walpurgite
A valid IMA mineral species - grandfathered
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About Walpurgite
Formula:
(BiO)4(UO2)(AsO4)2 · 2H2O
Colour:
yellow, orange-yellow; colourless to light yellow in transmitted light.
Lustre:
Adamantine, Greasy
Hardness:
3½
Specific Gravity:
6.59 (Calculated)
Crystal System:
Triclinic
Member of:
Name:
For the type locality, Walpurgis vein, Weißer Hirsch Mine, Schneeberg, Saxony, Germany.
This page provides mineralogical data about Walpurgite.
Unique Identifiers
Mindat ID:
4238
Long-form identifier:
mindat:1:1:4238:9
IMA Classification of Walpurgite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Bi3+4O4(U6+O2)(As5+O4)2·2H2O
First published:
1871
Classification of Walpurgite
8.EA.05
8 : PHOSPHATES, ARSENATES, VANADATES
E : Uranyl phosphates and arsenates
A : UO2:RO4 = 1:2
8 : PHOSPHATES, ARSENATES, VANADATES
E : Uranyl phosphates and arsenates
A : UO2:RO4 = 1:2
40.5.9.1
40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
5 : AXO4·xH2O
40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
5 : AXO4·xH2O
20.6.6
20 : Arsenates (also arsenates with phosphate, but without other anions)
6 : Arsenates of Bi
20 : Arsenates (also arsenates with phosphate, but without other anions)
6 : Arsenates of Bi
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Wpg | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Wl | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Physical Properties of Walpurgite
Adamantine, Greasy
Transparency:
Transparent, Translucent
Colour:
Yellow, orange-yellow; colourless to light yellow in transmitted light.
Streak:
Pale brownish yellow
Hardness:
3½ on Mohs scale
Cleavage:
Perfect
On {010}, perfect.
On {010}, perfect.
Density:
6.59 g/cm3 (Calculated)
Optical Data of Walpurgite
Type:
Biaxial (-)
RI values:
nα = 1.871 - 1.90 nβ = 1.975 - 2.00 nγ = 2.005 - 2.05
2V:
Measured: 50° to 60°, Calculated: 54° to 74°
Max. Birefringence:
δ = 0.134 - 0.150
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
Pleochroism:
Weak
Comments:
X = colorless; Y = Z = very faint greenish yellow.
Chemistry of Walpurgite
Mindat Formula:
(BiO)4(UO2)(AsO4)2 · 2H2O
Element Weights:
Crystallography of Walpurgite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 7.135(2) Å, b = 10.426(4) Å, c = 5.494(1) Å
α = 101.47(2)°, β = 110.82(2)°, γ = 88.20(2)°
α = 101.47(2)°, β = 110.82(2)°, γ = 88.20(2)°
Ratio:
a:b:c = 0.684 : 1 : 0.527
Unit Cell V:
374.04 ų (Calculated from Unit Cell)
Z:
1
Morphology:
Crystals lath-like [001] and tabular {010} with an oblique termination. Occurs also as sub-parallel aggregates and radial groups.
Twinning:
Twin plane and composition surface {010}, common, the twinned aggregates pseudo-monoclinic (resembling gypsum).
Crystal Structure
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
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CIF File Best | x | y | z | a | b | c
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Labels
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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) |
|---|---|---|---|---|---|---|---|
| 0015687 | Walpurgite | Mereiter K (1982) The crystal structure of walpurgite,(UO2)Bi4O4(AsO4)2*2H2O Tschermaks Mineralogische und Petrographische Mitteilungen 30 129-139 | 1982 | Schneeberg, Germany | 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 |
|---|---|
| 3.128 Å | (100) |
| 10.257 Å | (41) |
| 3.059 Å | (38) |
| 3.268 Å | (32) |
| 2.739 Å | (26) |
| 3.400 Å | (23) |
| 2.188 Å | (20) |
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] | |
| 47d : [Arsenates, antimonates, selenates, bismuthinates] |
Type Occurrence of Walpurgite
Place of Conservation of Type Material:
Mining Academy, Freiberg, Germany, 21779
Associated Minerals at Type Locality:
Synonyms of Walpurgite
Other Language Names for Walpurgite
Relationship of Walpurgite to other Species
Member of:
Other Members of Walpurgite Group:
| Orthowalpurgite | (BiO)4(UO2)(AsO4)2 · 2H2O | Orth. mmm(2/m2/m2/m) : Pbcm |
| Phosphowalpurgite | (BiO)4(UO2)(PO4)2 · 2H2O | Tric. 1 : P1 |
Common Associates
Associations Based on Photo Data:
| 27 photos of Walpurgite associated with Mixite | BiCu6(AsO4)3(OH)6 · 3H2O |
| 10 photos of Walpurgite associated with Quartz | SiO2 |
| 9 photos of Walpurgite associated with Atelestite | Bi2(AsO4)O(OH) |
| 8 photos of Walpurgite associated with Metatorbernite | Cu(UO2)2(PO4)2 · 8H2O |
| 7 photos of Walpurgite associated with Bariopharmacosiderite | Ba0.5Fe3+4(AsO4)3(OH)4 · 5H2O |
| 4 photos of Walpurgite associated with Zeunerite | Cu(UO2)2(AsO4)2 · 12H2O |
| 4 photos of Walpurgite associated with Tetrahedrite Group | M2(A6)M1(B4 C2)X3(D4)S1(Y12)S2(Z) |
| 4 photos of Walpurgite associated with Orthowalpurgite | (BiO)4(UO2)(AsO4)2 · 2H2O |
| 3 photos of Walpurgite associated with Eulytine | Bi4(SiO4)3 |
| 3 photos of Walpurgite associated with 'Cuproroméite' | Cu2Sb2(O,OH)7 |
Related Minerals - Strunz-mindat Grouping
| 8.EA.05 | Phosphowalpurgite | (BiO)4(UO2)(PO4)2 · 2H2O |
| 8.EA.05 | Orthowalpurgite | (BiO)4(UO2)(AsO4)2 · 2H2O |
| 8.EA.10 | Hallimondite | Pb2(UO2)(AsO4)2 · nH2O |
| 8.EA.10 | Parsonsite | Pb2(UO2)(PO4)2 |
| 8.EA.15 | Ulrichite | CaCu(UO2)(PO4)2 · 4H2O |
| 8.EA.20 | Lakebogaite | CaNaFe3+2H(UO2)2(PO4)4(OH)2 · 8H2O |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 16.0417% | 4,010,425 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 0.0000% | 0 | β, γ |
For comparison:
- Banana: ~15 Bq per fruit
- Granite: 1,000–3,000 Bq/kg
- EU exemption limit: 10,000 Bq/kg
Note: Risk is shown relative to daily recommended maximum exposure to non-background radiation of 1000 µSv/year. Note that natural background radiation averages around 2400 µSv/year so in reality these risks are probably extremely overstated! With infrequent handling and safe storage natural radioactive minerals do not usually pose much risk.
Interactive Simulator:
Note: The mass selector refers to the mass of radioactive mineral present, not the full specimen, also be aware that the matrix may also be radioactive, possibly more radioactive than this mineral!
Activity: –
| Distance | Dose rate | Risk |
|---|---|---|
| 1 cm | ||
| 10 cm | ||
| 1 m |
The external dose rate (D) from a radioactive mineral is estimated by summing the gamma radiation contributions from its Uranium, Thorium, and Potassium content, disregarding daughter-product which may have a significant effect in some cases (eg 'pitchblende'). This involves multiplying the activity (A, in Bq) of each element by its specific gamma ray constant (Γ), which accounts for its unique gamma emissions. The total unshielded dose at 1 cm is then scaled by the square of the distance (r, in cm) and multiplied by a shielding factor (μshield). This calculation provides a 'worst-case' or 'maximum risk' estimate because it assumes the sample is a point source and entirely neglects any self-shielding where radiation is absorbed within the mineral itself, meaning actual doses will typically be lower. The resulting dose rate (D) is expressed in microsieverts per hour (μSv/h).
D = ((AU × ΓU) + (ATh × ΓTh) + (AK × ΓK)) / r2 × μshield
Other Information
Notes:
Radioactive
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 Walpurgite
mindat.org URL:
https://www.mindat.org/min-4238.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 Walpurgite
Reference List:
Zepharovich, Victor Ritter (1873) Mineralogisches Lexicon für das Kaiserthum Österreich - II. Band. 1858-1872. Verlag Wilhelm Braumüller, Wien. 436pp. p.341 - (Cites Lindacker in Vogl (1857) relating to Waltherite)
Bertrand, Emile (1881) Sur la Waltherite [walpurgite] de Joachimsthal ; sur la Voltzine de Joachimsthal ; forme cristalline de l'eulytine. Bulletin de Minéralogie, 4 (3) 58-63 doi:10.3406/bulmi.1881.1628pp.58-59 - (as waltherite)
Larsen, Esper S. (1921) The microscopic determination of the nonopaque minerals. Bulletin 679. US Geological Survey doi:10.3133/b679 p.155
Frondel, Clifford (1943) The mineralogy of the oxides and carbonates of bismuth. American Mineralogist, 28 (9-10) 521-535 (as waltherite)
Evans, Howard T. (1950) Studies of uranium minerals (VI): Walpurgite. American Mineralogist, 35 (11-12) 1021-1027
Mereiter, K. (1982) The crystal structure of walpurgite, (UO2)Bi4O4(AsO4)2·2H2O. TMPM Tschermaks Mineralogische und Petrographische Mitteilungen, 30 (2) 129-139 doi:10.1007/bf01082500
Dunn, P. J.; Cabri, L. J.; Clark, A. M.; Fleischer, M. (1983) New mineral names. American Mineralogist, 68 (7-8). 849-852
Krause, Werner, Effenberger, Herta, Brandstätter, Franz (1995) Orthowalpurgite (UO2)Bi4O4(AsO4)2-2H2O, a new mineral from the Black Forest, Germany. European Journal of Mineralogy, 7 (6) 1313-1324 doi:10.1127/ejm/7/6/1313
Localities for Walpurgite
Showing 47 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.
Czech Republic | |
| Plášil J. et al. (2011) |
| Vogl (1857) +1 other reference |
| Palache et al. (1951) +1 other reference | |
| Škácha et al. (2014) +1 other reference | |
| Sejkora et al. (2002) |
| Viktor Goliáš et al. (2016) |
| Bradna |
Egypt | |
| 52 (2) +1 other reference |
Europe | |
| Sejkora et al. (2009) |
France | |
| Queneau (n.d.) |
Germany | |
| Walenta (1995) |
| Slotta (2004) |
| |
| |
| Walenta (1992) | |
| Markl (1992) |
| |
| Steen (2007) | |
| Tröger (2009) |
| Wittern (2001) |
| Schnorrer (1995) +1 other reference |
| Massanek et al. (2005) +1 other reference |
| Massanek et al. (2005) | |
| Martin et al. (1992) +1 other reference | |
| Massanek et al. (2005) | |
| Palache et al. (1951) | |
| A. Weisbach (1871) +2 other references |
| Massanek et al. (2005) |
| Schlegel et al. (1996) | |
| Massanek et al. (2005) | |
| Gröbner et al. (2006) +1 other reference |
| Massanek et al. (2005) |
| Wittern (2001) |
| Stephan Wolfsried collection |
| Gröbner et al. (2007) +1 other reference | |
Namibia | |
| Schnaitmann et al. (2007) |
| von Bezing (2007) | |
Poland | |
| Mochnacka et al. (2000) +1 other reference |
| Kozłowski et al. (2016) | |
| Kozłowski et al. (2018) |
Portugal | |
| Luis Martins collection |
Switzerland | |
| Meisser (2012) |
Tajikistan | |
| Chernikov et al. (1997) |
UK | |
| Braithwaite et al. (1990) |
| Knight (1978) +2 other references | |
| R. S. W. Braithwaite and J. R. Knight (1990) +1 other reference |
USA | |
| Troxel et al. (1962) +2 other references |
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Jáchymov, Karlovy Vary District, Karlovy Vary Region, Czech Republic