Ianthinite
A valid IMA mineral species - grandfathered
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About Ianthinite
Formula:
U4+(UO2)5O7 · 10H2O
Colour:
Violet-black; dark violet in transmitted light
Lustre:
Vitreous, Sub-Metallic
Hardness:
2 - 3
Specific Gravity:
5.16
Crystal System:
Orthorhombic
Name:
From the Greek ιάνθινος ("ianthinos"), violet colored, in allusion to its color.
Not very stable under ambient conditions; will dehydrate to schoepite (while becoming yellow and opaque) and further members of the schoepite group.
May be confused with nollmotzite.
Sheets in the crystal structure are similar to those in rameauite, spriggite and wyartite.
May be confused with nollmotzite.
Sheets in the crystal structure are similar to those in rameauite, spriggite and wyartite.
Unique Identifiers
Mindat ID:
2000
Long-form identifier:
mindat:1:1:2000:4
Similar Names
| Ianthinite (of Bignand) | A synonym of Wyartite |
IMA Classification of Ianthinite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
U4+2(U6+O2)4O6(OH)4·9H2O
First published:
1926
Classification of Ianthinite
4.GA.10
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
G : Uranyl Hydroxides
A : Without additional cations
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
G : Uranyl Hydroxides
A : Without additional cations
Dana 7th ed.:
5.6.1.1
5.6.1.1
5 : OXIDES CONTAINING URANIUM OR THORIUM
6 : AX6O17·xH2O
5 : OXIDES CONTAINING URANIUM OR THORIUM
6 : AX6O17·xH2O
7.16.7
7 : Oxides and Hydroxides
16 : Oxides of U
7 : Oxides and Hydroxides
16 : Oxides 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 |
|---|---|---|
| Ian | 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 Ianthinite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Ianthinite
Vitreous, Sub-Metallic
Transparency:
Transparent, Translucent
Colour:
Violet-black; dark violet in transmitted light
Comment:
on exposure to air, turns violet-brown, pale brown, then greenish yellow or yellow;
Streak:
Brown, violet
Hardness:
2 - 3 on Mohs scale
Tenacity:
Flexible
Cleavage:
Perfect
Perfect on {001}; {100}, good.
Perfect on {001}; {100}, good.
Fracture:
Conchoidal
Density:
5.16(5) g/cm3 (Measured) 5.00 g/cm3 (Calculated)
Optical Data of Ianthinite
Type:
Biaxial (-)
RI values:
nα = 1.674(3) nβ = 1.90(2) nγ = 1.92(2)
2V:
Measured: 58° , Calculated: 30°
Max. Birefringence:
δ = 0.246
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:
r > v perceptible
Pleochroism:
Strong
Comments:
X = c = colourless
Y = b = violet
Z = a = dark violet
Y = b = violet
Z = a = dark violet
Chemistry of Ianthinite
Mindat Formula:
U4+(UO2)5O7 · 10H2O
Elements listed:
Crystallography of Ianthinite
Crystal System:
Orthorhombic
Class (H-M):
mm2 - Pyramidal
Space Group:
Amm2
Cell Parameters:
a = 11.52(5) Å, b = 7.15(2) Å, c = 30.3(1) Å
Ratio:
a:b:c = 1.611 : 1 : 4.238
Unit Cell V:
2,495.75 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Tiny rectangular plates {001} elongated [010]. Also prismatic [010], or thick tabular {001}.
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
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Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
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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) |
|---|---|---|---|---|---|---|---|
| 0013139 | Ianthinite | Burns P C, Finch R J, Hawthorne F C, Miller M L, Ewing R C (1997) The crystal structure of ianthinite, [U4+2(UO2)4O6(OH)4](H2O)5: a possible phase for Pu4+ incorporation during the oxidation of spent nuclear fuel Journal of Nuclear Materials 249 199-206 | 1997 | Shinkolobwe mine, Shaba, southern Congo | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.63 Å | (FF) |
| 3.81 Å | (m) |
| 3.24 Å | (m) |
| 3.59 Å | (fm) |
| 3.35 Å | (fm) |
| 2.61 Å | (f) |
| 2.53 Å | (f) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 27 : Radioactive decay; auto-oxidation | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47f : [Uranyl (U⁶⁺) minerals] |
Type Occurrence of Ianthinite
General Appearance of Type Material:
Acicular crystals
Place of Conservation of Type Material:
n.d.
Associated Minerals at Type Locality:
Synonyms of Ianthinite
Other Language Names for Ianthinite
Common Associates
Associations Based on Photo Data:
| 31 photos of Ianthinite associated with Schoepite | (UO2)8O2(OH)12 · 12H2O |
| 6 photos of Ianthinite associated with Parauranophane | Ca(UO2)2(SiO3OH)2 · 5H2O |
| 4 photos of Ianthinite associated with Uraninite | UO2 |
| 2 photos of Ianthinite associated with Umohoite | (UO2)MoO4 · 2H2O |
| 2 photos of Ianthinite associated with Uranopilite | (UO2)6(SO4)O2(OH)6 · 14H2O |
| 2 photos of Ianthinite associated with Fourmarierite | Pb(UO2)4O3(OH)4 · 4H2O |
| 1 photo of Ianthinite associated with Curite | Pb3(H2O)2[(UO2)4O4(OH)3]2 |
| 1 photo of Ianthinite associated with Arsenuranospathite | Al(UO2)2(AsO4)2F · 20H2O |
| 1 photo of Ianthinite associated with Gypsum | CaSO4 · 2H2O |
| 1 photo of Ianthinite associated with Pyrite | FeS2 |
Related Minerals - Strunz-mindat Grouping
| 4.GA.05 | Paraschoepite | UO3 · 2H2O |
| 4.GA.05 | Metaschoepite | (UO2)8O2(OH)12 · 10H2O |
| 4.GA.05 | Schoepite | (UO2)8O2(OH)12 · 12H2O |
| 4.GA.15 | Metastudtite | UO4 · 2H2O |
| 4.GA.15 | Studtite | [(UO2)(O2)(H2O)2] · H2O |
| 4.GA.20 | Paulscherrerite | UO2(OH)2 |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 75.9539% | 18,988,475 | 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.
Alters upon heating with dilute hydrogen peroxide, turning brown, then yellow.
Alters upon heating with dilute hydrogen peroxide, turning brown, then yellow.
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 Ianthinite
mindat.org URL:
https://www.mindat.org/min-2000.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
References for Ianthinite
Reference List:
Billiet, Valère (1926) Détermination des indices de réfraction de la becquerélite, de la curite, de la kasolite, de la fourmariérite, de la parsonsite, de la dumontite, et de l'ianthinite. Bulletin de la Société française de Minéralogie, 49 (3). 136-140 doi:10.3406/bulmi.1926.4309
Palache, Charles (1934) Crystallography of the uranium oxides. American Mineralogist, 19 (7) 309-315
Bignand, Claude (1955) Sur les propriétés et les synthèses de quelques minéraux uranifères. Bulletin de Minéralogie, 78 (1) 1-26 doi:10.3406/bulmi.1955.4985
Guillemin, Claude; Protas, Jean (1959) Ianthinite et wyartite. Bulletin de la Société française de Minéralogie et de Cristallographie, 82 (1). 80-86 doi:10.3406/bulmi.1959.5308
Burns, Peter C.; Finch, Robert J.; Hawthorne, Frank C.; Miller, Mark L.; Ewing, Rodney C. (1997) The crystal structure of ianthinite, [U24+(UO2)4O6(OH)4(H2O)4](H2O)5: a possible phase for Pu4+ incorporation during the oxidation of spent nuclear fuel. Journal of Nuclear Materials, 249 (2-3). 199-206 doi:10.1016/s0022-3115(97)00212-2
Burns, Peter C. (2005) U6+ minerals and inorganic compounds: insights into an expanded structural hierarchy of crystal structures. The Canadian Mineralogist, 43 (6) 1839-1894 doi:10.2113/gscanmin.43.6.1839
Spano, Tyler L.; Olds, Travis A.; Malone, Addison; Barth, Brodie S.; Kaitschuck, Nicholas M.; Neu, Jennifer N.; Felton, Daniel E.; Miskowiec, Andrew (2026) Raman spectroscopic investigation of ianthinite [U24+(UO2)4O6(OH)4(H2O)4]·5H2O, a rare mixed-valence uranium oxide hydrate. American Mineralogist, 111 (3). 491-499 doi:10.2138/am-2025-9759
Localities for Ianthinite
Showing 36 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 | |
| Bottrill (2021) +1 other reference |
Brazil | |
| Pires et al. (2014) |
DR Congo (TL) | |
| Guillemin et al. (1959) +2 other references |
| Gauthier et al. (1989) | |
Egypt | |
| Hussein et al. (1988) |
France | |
| - (1998) |
| J. Chervet et G. Branche : ... +1 other reference | |
| - (1998) |
| J. Geffroy | |
| Marcel Roubault et al. (1960 -1965) +1 other reference |
| Lièvre et al. (2002) |
| Lièvre et al. (2002) |
| - (1998) |
| - (1998) | |
| - (1998) |
| Bariand et al. (1993) +1 other reference |
| Henriot et al. (1998) |
| - (1998) | |
Germany | |
| Kolitsch (1997) +3 other references |
| Walenta (1989) |
| |
| Weiß (1990) |
| Dill et al. (2010) | |
Greece | |
| Rieck et al. (2018) |
India | |
| Singh et al. (2015) |
| SINGH et al. (2014) |
| Kumar et al. (2008) |
Italy | |
| Olmi F. |
| Campostrini et al. (2006) |
Mexico | |
| |
| www.swri.org (2001) | |
Slovakia | |
| Koděra et al. (1986) |
| Koděra et al. (1986) |
USA | |
| Eckel et al. (1997) |
| Gross (1965) +1 other reference |
| Eckel et al. (1997) |
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Krunkelbach Valley Uranium deposit, Menzenschwand, St Blasien, Waldshut, Freiburg Region, Baden-Württemberg, Germany