Hallimondite
A valid IMA mineral species
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About Hallimondite
Arthur F. Hallimond
Formula:
Pb2(UO2)(AsO4)2 · nH2O
0 ≤ n ≤ 0.5
Colour:
Yellow
Lustre:
Sub-Adamantine
Hardness:
2½ - 3
Specific Gravity:
6.39
Crystal System:
Triclinic
Name:
Named in 1961 by Kurt Walenta and Wolfhard Wimmenauer in honor of Dr. Arthur Francis Hallimond [January 17, 1890 Saltburn, Yorkshire, England, UK - September 2, 1968 London, England, UK], British mineralogist, London, England, for his work with secondary uranium minerals, metallurgy of carbon steel, refractory materials, banded iron ores, and other researches. Hallimond was an early tester and innovator of geomagnetic measuring devices and worked on the geomagnetism of rocks. Additionally he developed equipment for determining the refractive index of liquid mixtures, magnetic separation of minerals, use of Polaroid filters to replace Nicol prisms, reflected light microscopy, and major advances in petrographic microscope design. He wrote important books on microscopy and, in retirement, consulted for the Vickers Microscope company, Chance-Pilkington Research Laboratories and to the Atomic Energy Research Establishment at Harwell. He named the species bassetite and uranospathite.
Unique Identifiers
Mindat ID:
1807
Long-form identifier:
mindat:1:1:1807:0
IMA Classification of Hallimondite
Approved
IMA Formula:
Pb2+2(U6+O2)(As5+O4)2·nH2O
Approval year:
1965
First published:
1965
Classification of Hallimondite
8.EA.10
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
40.2a.32.1
40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
2a : AB2(XO4)2·xH2O, containing (UO2)2+
40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
2a : AB2(XO4)2·xH2O, containing (UO2)2+
20.7.15
20 : Arsenates (also arsenates with phosphate, but without other anions)
7 : Arsenates of U
20 : Arsenates (also arsenates with phosphate, but without other anions)
7 : Arsenates of U
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 |
|---|---|---|
| Hll | 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 Hallimondite
Sub-Adamantine
Transparency:
Transparent, Translucent
Colour:
Yellow
Streak:
Pale yellow
Hardness:
2½ - 3 on Mohs scale
Hardness Data:
Estimated
Comment:
Estimated by analogy to parsonite.
Cleavage:
None Observed
Fracture:
Conchoidal
Density:
6.39 g/cm3 (Measured) 6.40 g/cm3 (Calculated)
Comment:
Measured using synthetic material.
Optical Data of Hallimondite
Type:
Biaxial (+)
RI values:
nα = 1.882(5) nγ = 1.915(5)
2V:
Measured: 80°
Max. Birefringence:
δ = 0.033
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:
Moderate
Dispersion:
r > v
Optical Extinction:
(100) Z' Λ c 11°; (010) X' Λ c 11°; (001) X' Λ b 9°
Due to the dispersion, extinction is not sharp when nicols are crossed and anomalous blue and brown interference colors can be observed.
Sometimes substantial variations in extinction angles can be
Due to the dispersion, extinction is not sharp when nicols are crossed and anomalous blue and brown interference colors can be observed.
Sometimes substantial variations in extinction angles can be
Pleochroism:
Weak
Comments:
X = pale yellow; Z = nearly colorless.
Comments:
Absorption: X > Z
Chemistry of Hallimondite
Mindat Formula:
Pb2(UO2)(AsO4)2 · nH2O
0 ≤ n ≤ 0.5
0 ≤ n ≤ 0.5
Element Weights:
Crystallography of Hallimondite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 7.123 Å, b = 10.469 Å, c = 6.844 Å
α = 100.34°, β = 94.48°, γ = 91.16°
α = 100.34°, β = 94.48°, γ = 91.16°
Ratio:
a:b:c = 0.68 : 1 : 0.654
Unit Cell V:
500.23 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Type material:
Flattened on {110} and {100} and more or less elongated along the c-axis. Observed forms are: a {100}, b {010}, c {001}, m {110}, n {610}, k {011}, q {018} and p {111}.
The largest faces are {110} and {100}. Medium {010} and {001}. Small {011} and {111}. The base, {001}, is striated parallel to the intersection with {010} (caused by {018}). A similar striation occurs on {100} parallel
the c-axis (caused by {610}).
Flattened on {110} and {100} and more or less elongated along the c-axis. Observed forms are: a {100}, b {010}, c {001}, m {110}, n {610}, k {011}, q {018} and p {111}.
The largest faces are {110} and {100}. Medium {010} and {001}. Small {011} and {111}. The base, {001}, is striated parallel to the intersection with {010} (caused by {018}). A similar striation occurs on {100} parallel
the c-axis (caused by {610}).
Comment:
Cell parameters from Walenta (1965).
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) |
|---|---|---|---|---|---|---|---|
| 0003720 | Hallimondite | Locock A J, Burns P C, Flynn T M (2005) The role of water in the structures of synthetic hallimondite, Pb2[(UO2)(AsO4)2](H2O)n and synthetic parsonsite, Pb2[(UO2)(PO4)2](H2O)n, 0 < n < 0.5 American Mineralogist 90 240-246 |  | 2005 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.42 Å | (100b) |
| 2.85 Å | (80) |
| 4.42 Å | (60) |
| 3.03 Å | (60) |
| 4.26 Å | (50) |
| 3.33 Å | (50b) |
| 7.09 Å | (30) |
Type Occurrence of Hallimondite
General Appearance of Type Material:
Small well-developed crystals to 0.4 mm and fine-grained coatings in cavities and fractures of quartz (hornstone). Formed later than hügelite and before mimetite. Sometimes as oriented intergrowths with hügelite, sharing the c-axis.
Place of Conservation of Type Material:
n.d.
Geological Setting of Type Material:
Oxidation zone of a deposit containing sulfides, considerable native arsenic, and uranium minerals.
Associated Minerals at Type Locality:
Synonyms of Hallimondite
Other Language Names for Hallimondite
Relationship of Hallimondite to other Species
Forms a series with:
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 8.EA.05 | Phosphowalpurgite | (BiO)4(UO2)(PO4)2 · 2H2O |
| 8.EA.05 | Walpurgite | (BiO)4(UO2)(AsO4)2 · 2H2O |
| 8.EA.05 | Orthowalpurgite | (BiO)4(UO2)(AsO4)2 · 2H2O |
| 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) | 24.2817% | 6,070,425 | 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
Fluorescence of Hallimondite
Not fluorescent
Other Information
Thermal Behaviour:
The DTA curve of synthetic hallimondite shows a distinct endothermic effect at 940 °C.
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 Hallimondite
mindat.org URL:
https://www.mindat.org/min-1807.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Hallimondite
Reference List:
Walenta, Kurt (1965) Hallimondite, a new uranium mineral from the Michael Mine near Reichenbach (Black Forest, Germany). American Mineralogist, 50 (9). 1143-1157
Locock, Andrew J., Burns, Peter C., Flynn, Theodore M. (2005) The role of water in the structures of synthetic hallimondite, Pb2[(UO2)(AsO4)2](H2O)n and synthetic parsonsite, Pb2[(UO2)(PO4)2](H2O)n, 0 ≤n≤ 0.5. American Mineralogist, 90 (1) 240-246 doi:10.2138/am.2005.1705
Localities for Hallimondite
Showing 3 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.
Germany (TL) | |
| Walenta (1965) +2 other references |
| Markl et al. (2011) |
| Aufschluss 69/ (7+8) +1 other reference |
Quick NavTopAbout HallimonditeUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionType Occurrence SynonymsOther LanguagesRelationshipsCommon AssociatesStrunz-MindatRadioactivityFluorescence Other InformationInternet Links References Localities Locality List
Michael Mine, Weiler, Seelbach, Seelbach, Ortenaukreis, Freiburg Region, Baden-Württemberg, Germany