Therasiaite
A valid IMA mineral species
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About Therasiaite
Formula:
(NH4)3KNa2Fe2+Fe3+(SO4)3Cl5
Colour:
Brown to dark brown
Specific Gravity:
2.41
Crystal System:
Monoclinic
Name:
The name is for the type locality, Therasia, one of the ancient names for Vulcano island (from the Greek θηρασια, warm earth).
Decomposes in air after a couple of weeks, but stable under nitrogen.
Unique Identifiers
Mindat ID:
43926
Long-form identifier:
mindat:1:1:43926:2
IMA Classification of Therasiaite
Approved
Approval year:
2013
First published:
2014
Classification of Therasiaite
7.BC.65
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
B : Sulfates (selenates, etc.) with additional anions, without H2O
C : With medium-sized and large cations
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
B : Sulfates (selenates, etc.) with additional anions, without H2O
C : With medium-sized and large cations
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 |
|---|---|---|
| The | 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 Therasiaite
Colour:
Brown to dark brown
Density:
2.41(1) g/cm3 (Measured) 2.395 g/cm3 (Calculated)
Optical Data of Therasiaite
Type:
Biaxial (-)
RI values:
nα = 1.585(3) nβ = 1.615(3) nγ = 1.630(3)
Max. Birefringence:
δ = 0.045
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
Chemistry of Therasiaite
Mindat Formula:
(NH4)3KNa2Fe2+Fe3+(SO4)3Cl5
Element Weights:
Crystallography of Therasiaite
Crystal System:
Monoclinic
Class (H-M):
m - Domatic
Space Group:
Bb
Setting:
Cc
Cell Parameters:
a = 18.284(4) Å, b = 12.073(2) Å, c = 9.535(2) Å
β = 108.10(1)°, γ = °
β = 108.10(1)°, γ = °
Ratio:
a:b:c = 1.514 : 1 : 0.79
Unit Cell V:
2000.6 ų
Z:
4
Morphology:
Equant to short prismatic 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) |
|---|---|---|---|---|---|---|---|
| 0020043 | Therasiaite | Demartin F, Castellano C, Campostrini I (2014) Therasiaite, (NH4)3KNa2Fe2+Fe3+(SO4)3Cl5, a new sulfate chloride from La Fossa Crater, Vulcano, Aeolian islands, Italy Mineralogical Magazine 78 203-213 | 2014 | La Fossa Crater, Vulcano, Aeolian islands, Italy | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.297 Å | (28) |
| 3.208 Å | (14) |
| 3.008 Å | (12) |
| 2.942 Å | (11) |
| 2.812 Å | (100) |
| 2.749 Å | (9) |
| 2.664 Å | (77) |
Reference:
Comments:
From Type Description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 45a : [Sulfates, arsenates, selenates, antimonates] | |
| 45b : [Other oxidized fumarolic minerals] |
Type Occurrence of Therasiaite
General Appearance of Type Material:
On a pyroclastic breccia as brown to dark brown equant to short prismatic crystals up to 0.1 mm in length.
Place of Conservation of Type Material:
Type material is deposited in the Reference Collection of the Dipartimento di Chimica, University of Milan, Milan, Italy, sample number 2013-01
Geological Setting of Type Material:
In a medium-temperature (~250°C) intracrater active fumarole.
Associated Minerals at Type Locality:
Synonyms of Therasiaite
Other Language Names for Therasiaite
Dutch:Therasiaiet
German:Therasiait
Common Associates
Associations Based on Photo Data:
| 1 photo of Therasiaite associated with Kremersite | (NH4,K)2[Fe3+Cl5(H2O)] |
| 1 photo of Therasiaite associated with Adranosite | (NH4)4NaAl2(SO4)4Cl(OH)2 |
| 1 photo of Therasiaite associated with Alunite | KAl3(SO4)2(OH)6 |
| 1 photo of Therasiaite associated with Native Sulphur | S8 |
Related Minerals - Strunz-mindat Grouping
| 7.BC. | Viskontite | Pb5Cu2(SO4)3(SeO3)(OH)6 |
| 7.BC. | Zincochenite | Pb4Zn(OH)6(SO4)2 |
| 7.BC. | D'Ansite-(Mn) | Na21Mn2+(SO4)10Cl3 |
| 7.BC. | D'Ansite-(Fe) | Na21Fe2+(SO4)10Cl3 |
| 7.BC. | Acmonidesite | (NH4,K,Pb)8NaFe2+4(SO4)5Cl8 |
| 7.BC. | Adranosite | (NH4)4NaAl2(SO4)4Cl(OH)2 |
| 7.BC. | Chromviskontite | Pb5Cu2(CrO4)3(SeO3)(OH)6 |
| 7.BC. | Backite | Pb2AlTeO6Cl |
| 7.BC. | Adranosite-(Fe) | (NH4)4NaFe3+2(SO4)4Cl(OH)2 |
| 7.BC. | Agaite | Pb3CuTeO5(OH)2(CO3) |
| 7.BC. | Wildcatite | CaFe3+Te6+O5(OH) |
| 7.BC. | Hagstromite | Pb8Cu2+(Te6+O6)2(CO3)Cl4 |
| 7.BC.05 | D'Ansite | Na21Mg(SO4)10Cl3 |
| 7.BC.07 | 'Apatelite' | Fe3(SO4)2(OH)5 · 0.5H2O |
| 7.BC.07 | 'Unnamed (Ba-Fe Vanadate)' | Ba, Fe, V, O, H |
| 7.BC.10 | Jarosite | KFe3+3(SO4)2(OH)6 |
| 7.BC.10 | Dorallcharite | TlFe3+3(SO4)2(OH)6 |
| 7.BC.10 | Argentojarosite | AgFe3+3(SO4)2(OH)6 |
| 7.BC.10 | Natroalunite | NaAl3(SO4)2(OH)6 |
| 7.BC.10 | Natrojarosite | NaFe3(SO4)2(OH)6 |
| 7.BC.10 | Beaverite-(Cu) | Pb(Fe3+2Cu)(SO4)2(OH)6 |
| 7.BC.10 | Beaverite-(Zn) | Pb(Fe3+2Zn)(SO4)2(OH)6 |
| 7.BC.10 | Walthierite | Ba0.5Al3(SO4)2(OH)6 |
| 7.BC.10 | Huangite | Ca0.5Al3(SO4)2(OH)6 |
| 7.BC.10 | 'Natroalunite-2c' | (Na,Ca0.5,K)Al3(SO4)2(OH)6 |
| 7.BC.10 | Alunite | KAl3(SO4)2(OH)6 |
| 7.BC.10 | Plumbojarosite | Pb0.5Fe3+3(SO4)2(OH)6 |
| 7.BC.10 | Karlseifertite | Pb(Ga2Ge)(AsO4)2(OH)6 |
| 7.BC.10 | Hydroniumjarosite | (H3O)Fe3+3(SO4)2(OH)6 |
| 7.BC.10 | Ammonioalunite | (NH4)Al3(SO4)2(OH)6 |
| 7.BC.10 | Ammoniojarosite | (NH4)Fe3+3(SO4)2(OH)6 |
| 7.BC.10 | Osarizawaite | Pb(Al2Cu2+)(SO4)2(OH)6 |
| 7.BC.10 | Schlossmacherite | (H3O)Al3(SO4)2(OH)6 |
| 7.BC.15 | Ye'elimite | Ca4Al6(SO4)O12 |
| 7.BC.20 | Nabokoite | KCu7(SO4)5(Te4+O3)OCl |
| 7.BC.20 | Puninite | Na2Cu3O(SO4)3 |
| 7.BC.20 | Atlasovite | K(BiO)Cu6Fe3+(SO4)5O3Cl |
| 7.BC.25 | Chlorothionite | K2Cu(SO4)Cl2 |
| 7.BC.30 | Euchlorine | KNaCu3(SO4)3O |
| 7.BC.30 | Fedotovite | K2Cu3(SO4)3O |
| 7.BC.35 | Kamchatkite | KCu3(SO4)2OCl |
| 7.BC.40 | Piypite | K4Cu4O2(SO4)4 · (Na,Cu)Cl |
| 7.BC.45 | Alumoklyuchevskite | K3Cu3(Al,Fe3+)(SO4)4O2 |
| 7.BC.45 | Belousovite | KZn(SO4)Cl |
| 7.BC.45 | Klyuchevskite | K3Cu3(Fe3+,Al)(SO4)4O2 |
| 7.BC.47 | Müllerite | Pb2Fe3+(Te6+O6)Cl |
| 7.BC.50 | Caledonite | Pb5Cu2(SO4)3(CO3)(OH)6 |
| 7.BC.50 | Elasmochloite | Na3Cu6BiO4(SO4)5 |
| 7.BC.52 | Eleomelanite | (K2Pb)Cu4O2(SO4)4 |
| 7.BC.55 | Falgarite | K4(VO)3(SO4)5 |
| 7.BC.55 | Wherryite | Pb7Cu2(SO4)4(SiO4)2(OH)2 |
| 7.BC.57 | Krasheninnikovite | KNa2CaMg(SO4)3F |
| 7.BC.60 | Wulffite | K3NaCu4O2(SO4)4 |
| 7.BC.60 | Parawulffite | K5Na3Cu8O4(SO4)8 |
| 7.BC.60 | Mammothite | Pb6Cu4AlSb5+O2(OH)16Cl4(SO4)2 |
| 7.BC.62 | Shuvalovite | K2(Ca2Na)(SO4)3F |
| 7.BC.65 | Saccoite | Ca2Mn3+2F(OH)8 · 0.5(SO4) |
| 7.BC.65 | Linarite | PbCu(SO4)(OH)2 |
| 7.BC.65 | Franksousaite | PbCu(Se6+O4)(OH)2 |
| 7.BC.65 | Munakataite | Pb2Cu2(Se4+O3)(SO4)(OH)4 |
| 7.BC.65 | Schmiederite | Pb2Cu2(Se6+O4)(Se4+O3)(OH)4 |
| 7.BC.70 | Chenite | Pb4Cu(SO4)2(OH)6 |
| 7.BC.75 | Krivovichevite | Pb3Al(OH)6(SO4)(OH) |
| 7.BC.80 | Anhydrokainite | KMg(SO4)Cl |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 0.0000% | 0 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 5.4581% | 1,692 | 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 Therasiaite
mindat.org URL:
https://www.mindat.org/min-43926.html
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References for Therasiaite
Reference List:
Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2013) New minerals and nomenclature modifications approved in 2013. CNMNC Newsletter No.17. Mineralogical Magazine, 77 (7) 2997-3005 doi:10.1180/minmag.2013.077.7.09
Localities for Therasiaite
Showing 1 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.
Italy (TL) | |
| Williams et al. (2013) +1 other reference |
Quick NavTopAbout TherasiaiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesCommon AssociatesStrunz-MindatRadioactivityOther InformationInternet Links References Localities Locality List
La Fossa crater, Vulcano Island, Lipari, Eolie Islands, Metropolitan City of Messina, Sicily, Italy