Ichnusaite
A valid IMA mineral species
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About Ichnusaite
Sardinia, Italy
Formula:
Th(MoO4)2 · 3H2O
Colour:
Colorless
Lustre:
Adamantine, Pearly
Specific Gravity:
4.262 (Calculated)
Crystal System:
Monoclinic
Name:
The name is from the old Greek name of Sardinia, Ιχνουσσα, ichnusa.
New structure type. (pronounced iknusa-ait)
Unique Identifiers
Mindat ID:
45998
Long-form identifier:
mindat:1:1:45998:3
IMA Classification of Ichnusaite
Approved
IMA Formula:
Th4+(Mo6+O4)2·3H2O
Approval year:
2013
First published:
2014
Classification of Ichnusaite
7.GB.65
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
G : Molybdates, Wolframates and Niobates
B : With additional anions and/or H2O
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
G : Molybdates, Wolframates and Niobates
B : With additional anions and/or H2O
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 |
|---|---|---|
| Ich | 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 Ichnusaite
Adamantine, Pearly
Transparency:
Transparent
Colour:
Colorless
Streak:
White
Tenacity:
Brittle
Cleavage:
Perfect
{100}
{100}
Density:
4.262 g/cm3 (Calculated)
Comment:
Could not be measured on type material
Chemistry of Ichnusaite
Mindat Formula:
Th(MoO4)2 · 3H2O
Element Weights:
Elements listed:
Crystallography of Ichnusaite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/c
Setting:
P21/c
Cell Parameters:
a = 9.6797(12) Å, b = 10.3771(13) Å, c = 9.3782(12) Å
β = 90.00(1)°
β = 90.00(1)°
Ratio:
a:b:c = 0.933 : 1 : 0.904
Unit Cell V:
942 ų
Z:
4
Morphology:
Thin {100} tabular crystals
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) |
|---|---|---|---|---|---|---|---|
| 0020407 | Ichnusaite | Orlandi P, Biagioni C, Bindi L, Nestola F (2014) Ichnusaite, Th(MoO4)2*3H2O, the first natural thorium molybdate: occurrence, description, and crystal structure American Mineralogist 99 2089-2094 | 2014 | Su Seinargiu, Sarroch, Cagliari, Sardinia, Italy | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 9.7 Å | (mw) |
| 5.66 Å | (m) |
| 5.19 Å | (mw) |
| 4.69 Å | (mw) |
| 3.930 Å | (m) |
| 3.479 Å | (s) |
| 3.257 Å | (s) |
| 3.074 Å | (m) |
Reference:
Comments:
From 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] |
Type Occurrence of Ichnusaite
General Appearance of Type Material:
Thin {100} tabular crystals, up to 200 μm in length
Place of Conservation of Type Material:
Type material is deposited in the collections of the Museo di Storia Naturale, Universita` di Pisa, Calci (Pisa), Italy, catalogue number 19679
Geological Setting of Type Material:
Alteration of molybdenite ores under basic pH conditions.
Associated Minerals at Type Locality:
Synonyms of Ichnusaite
Other Language Names for Ichnusaite
Dutch:Ichnusaiet
German:Ichnusait
Common Associates
Associations Based on Photo Data:
| 4 photos of Ichnusaite associated with Nuragheite | Th(MoO4)2 · H2O |
| 2 photos of Ichnusaite associated with Kingsgateite | ZrMo6+2O7(OH)2 · 2H2O |
| 1 photo of Ichnusaite associated with Tooeleite | Fe3+6(As3+O3)4(SO4)(OH)4 · 4H2O |
| 1 photo of Ichnusaite associated with Scorodite | Fe3+AsO4 · 2H2O |
| 1 photo of Ichnusaite associated with Gelosaite | BiMo6+(2-5x)Mo5+6xO7(OH) · H2O |
| 1 photo of Ichnusaite associated with Molybdenite | MoS2 |
| 1 photo of Ichnusaite associated with Quartz | SiO2 |
Related Minerals - Strunz-mindat Grouping
| 7.GB. | Stunorthropite | (NH4)4[Mo2O6(MoO4)2] |
| 7.GB. | Hartkoppeite | Ca4Mn2+Mo6+6As5+4O32(OH)2(H2O)14 · 5H2O |
| 7.GB. | Wangpuite | K3(PO4)(Mo12O36) |
| 7.GB. | Alexearlite | Hg3S2(MoO4) |
| 7.GB. | Ootannite | Th4+2W6+4O16 · 5H2O |
| 7.GB. | Natromolybdite | Na2MoO4 · 2H2O |
| 7.GB. | Marsaalamite-(Y) | Y(MoO4)(OH) |
| 7.GB.05 | Lindgrenite | Cu3(MoO4)2(OH)2 |
| 7.GB.10 | Szenicsite | Cu3(MoO4)(OH)4 |
| 7.GB.15 | 'UM1999-38-WO:CrV' | (V, Cr, W, O, H) [V:Cr:W ratio about 2:1:3] |
| 7.GB.15 | Huenite | Cu4(MoO4)3(OH)2 |
| 7.GB.15 | Cuprotungstite | Cu2(WO4)(OH)2 |
| 7.GB.20 | Phyllotungstite | (H2O,M)x(W,Fe)(O,OH)3 · yH2O (M = Ca, Cs, Pb or K) |
| 7.GB.25 | Rankachite | Ca0.5(V4+,V5+)(W6+,Fe3+)2O8(OH) · 2H2O |
| 7.GB.30 | Ferrimolybdite | Fe2(MoO4)3 · nH2O |
| 7.GB.35 | Mpororoite | WAlO3(OH)3 · 2(H2O) |
| 7.GB.35 | Anthoinite | AlWO3(OH)3 |
| 7.GB.40 | Obradovicite-KCu | [K2(H2O)17Cu(H2O)6][Mo8As2Fe3+3O34(OH)3] |
| 7.GB.45 | Paramendozavilite | [KAl4(H2O)30][Mo12P6Fe3+6O60(OH)13] |
| 7.GB.45 | Mendozavilite-NaFe | [Na2(H2O)15Fe3+(H2O)6][Mo8P2Fe3+3O35(OH)2] |
| 7.GB.45 | Obradovicite-NaCu | Na2(H2O)17Cu(H2O)6][Mo8As2Fe3+3O34(OH)3] |
| 7.GB.45 | Obradovicite-NaNa | [Na2(H2O)16Na(H2O)6][Mo8As2Fe3+3O33(OH)4] |
| 7.GB.50 | Tancaite-(Ce) | FeCe(MoO4)3 · 3H2O |
| 7.GB.50 | Mendozavilite-NaCu | [Na2(H2O)15Cu(H2O)6][Mo8P2Fe3+3O34(OH)3] |
| 7.GB.50 | Mendozavilite-KCa | [K2(H2O)15Ca(H2O)6][Mo8P2Fe3+3O34(OH)3] |
| 7.GB.60 | Peterandresenite | Mn4Nb6O19 · 14H2O |
| 7.GB.60 | Hansesmarkite | Ca2Mn2Nb6O19 · 20H2O |
| 7.GB.60 | Melcherite | Ba2Na2Mg[Nb6O19] · 6H2O |
| 7.GB.70 | Markascherite | Cu3(MoO4)(OH)4 |
| 7.GB.75 | Nuragheite | Th(MoO4)2 · H2O |
| 7.GB.80 | Ophirite | Ca2Mg4[Zn2Mn3+2(H2O)2(Fe3+W9O34)2] · 46H2O |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 0.0000% | 0 | α, β, γ |
| Thorium (Th) | 38.2902% | 1,531,608 | 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
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 Ichnusaite
mindat.org URL:
https://www.mindat.org/min-45998.html
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References for Ichnusaite
Reference List:
Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2013) New minerals and nomenclature modifications approved in 2013. CNMNC Newsletter No 18. Mineralogical Magazine, 77 (8) 3249-3258 doi:10.1180/minmag.2013.077.8.15
Localities for Ichnusaite
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 | |
| Haupt et al. (2025) |
| Peter Elliott | |
Austria | |
| Steiner et al. (2020) |
Italy (TL) | |
| Orlandi et al. (2014) +1 other reference |
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Old 25 Pipe, Kingsgate, Gough Co., New South Wales, Australia