Arcanite
A valid IMA mineral species - grandfathered
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About Arcanite
Formula:
K2SO4
Colour:
Colourless, white, yellow
Hardness:
2
Specific Gravity:
2.663
Crystal System:
Orthorhombic
Name:
Named in 1845 by Wilhelm Carl von Haidinger from the Latin "arcanum duplicatum," for double secret, a medieval alchemical name. The original material was an exudate on the surface of discarded railroad track ties that had been used in the Santa Ana tin mine, Trabuco Canyon, Santa Ana Mountains, Orange County, California, USA.
Type Locality:
Isostructural with:
Arcanite-Mascagnite Series.
This species was described and named based on artificial material and the type occurrence, which is anthropogenic (pine rail tie in a mine). It has since been identified in nature.
Note: Well-crystalline specimens on the market (e.g. those labelled from Poland, or anything that looks better than the photos of natural material at the head of this page) are grown artificially and are not natural minerals. See also spessartine arcanite.
This species was described and named based on artificial material and the type occurrence, which is anthropogenic (pine rail tie in a mine). It has since been identified in nature.
Note: Well-crystalline specimens on the market (e.g. those labelled from Poland, or anything that looks better than the photos of natural material at the head of this page) are grown artificially and are not natural minerals. See also spessartine arcanite.
Unique Identifiers
Mindat ID:
314
Long-form identifier:
mindat:1:1:314:6
Similar Names
| Acanite | A synonym of 'Askanite' | |
| Aragonite | A valid IMA mineral species - grandfathered | CaCO3 |
| Arcanit (of Haidinger) | A synonym of Aphthitalite | (K,Na)3Na(SO4)2 |
| Ercinita | A synonym of Harmotome | |
| Ercinite |
IMA Classification of Arcanite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
K2(SO4)
Classification of Arcanite
7.AD.05
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
A : Sulfates (selenates, etc.) without additional anions, without H2O
D : With only large cations
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
A : Sulfates (selenates, etc.) without additional anions, without H2O
D : With only large cations
28.2.1.2
28 : ANHYDROUS ACID AND NORMAL SULFATES
2 : A2XO4
28 : ANHYDROUS ACID AND NORMAL SULFATES
2 : A2XO4
25.1.4
25 : Sulphates
1 : Sulphates of the alkali metals and ammonium
25 : Sulphates
1 : Sulphates of the alkali metals and ammonium
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 |
|---|---|---|
| Acn | 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 Arcanite
Transparency:
Transparent, Translucent
Colour:
Colourless, white, yellow
Hardness:
2 on Mohs scale
Cleavage:
Distinct/Good
On {010} and {001}.
On {010} and {001}.
Density:
2.663 g/cm3 (Measured) 2.667 g/cm3 (Calculated)
Optical Data of Arcanite
Type:
Biaxial (+)
RI values:
nα = 1.4935 nβ = 1.4947 nγ = 1.4973
2V:
Measured: 67° , Calculated: 70°
Max. Birefringence:
δ = 0.004
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
Dispersion:
r > v strong
Chemistry of Arcanite
Mindat Formula:
K2SO4
Elements listed:
Crystallography of Arcanite
Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Cell Parameters:
a = 5.77 Å, b = 10.07 Å, c = 7.48 Å
Ratio:
a:b:c = 0.573 : 1 : 0.743
Unit Cell V:
434.62 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Thin tablets comprised of sixling cyclic twins bounded by {001}, {011}, and {112} (Santa Ana Mine). Artificial crystals frequently twinned.
Twinning:
On {110}, cyclic at times; pseudo-hexagonal groupings.
Comment:
Space Group: P nam (synthetic)
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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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) |
|---|---|---|---|---|---|---|---|
| 0009456 | Arcanite | McGinnety J A (1972) Redetermination of the structures of potassium sulphate and potassium chromate: the effect of electrostatic crystal forces upon observed bond length Acta Crystallographica B28 2845-2852 |  | 1972 | 0 | 293 | |
| 0018287 | Arcanite | Robinson M (1958) The crystal structures of beta-K2SO4 and of beta-K2PO3F _cod_database_code 1200011 Journal of Physical Chemistry 62 925-928 | 1958 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.903 Å | (100) |
| 3.001 Å | (77) |
| 2.886 Å | (53) |
| 4.176 Å | (28) |
| 2.422 Å | (25) |
| 2.089 Å | (25) |
| 2.082 Å | (25) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 3b: Earth’s earliest hydrosphere | >4.45 |
| 14 : Hot springs, geysers, and other subaerial geothermal minerals | |
| Stage 7: Great Oxidation Event | <2.4 |
| 45a : [Sulfates, arsenates, selenates, antimonates] | |
| 45b : [Other oxidized fumarolic minerals] | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 50 : Coal and/or oil shale minerals | <0.36 |
| 52 : Guano- and urine-derived minerals | <0.4 |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 54 : Coal and other mine fire minerals (see also #51 and #56) | |
| 55 : Anthropogenic mine minerals |
Type Occurrence of Arcanite
General Appearance of Type Material:
Thin tablets in wood.
Place of Conservation of Type Material:
University of California, Berkeley, California; Harvard University, Cambridge, Massachusetts, USA, 100763.
Geological Setting of Type Material:
Not applicable.
Synonyms of Arcanite
Other Language Names for Arcanite
Varieties of Arcanite
| Taylorite (of Dana) | Ammonium-bearing arcanite. Found in guano beds of the Chincha Islands, Peru |
Relationship of Arcanite to other Species
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 3 photos of Arcanite associated with Hematite | Fe2O3 |
| 2 photos of Arcanite associated with Piypite | K4Cu4O2(SO4)4 · (Na,Cu)Cl |
| 1 photo of Arcanite associated with 'Unnamed (Lyonsite-like Cu-Fe-Vanadate)' | (Cu,Zn)2(Fe,Al)2[(V,Mo,S,As)O4]3 |
| 1 photo of Arcanite associated with Alunite Group | A0.5-1 B3[SO4]2(OH)6 |
Related Minerals - Strunz-mindat Grouping
| 7.AD. | Bubnovaite | K2Na8Ca(SO4)6 |
| 7.AD. | Dobrovolskyite | Na4Ca(SO4)3 |
| 7.AD. | Calciolangbeinite | K2Ca2(SO4)3 |
| 7.AD. | Murphyite | Pb(Te6+O4) |
| 7.AD. | Cuprodobrovolskyite | Na4Cu(SO4)3 |
| 7.AD. | Kristjánite | KNa2H(SO4)2 |
| 7.AD.05 | Mascagnite | (NH4)2SO4 |
| 7.AD.10 | Mercallite | KHSO4 |
| 7.AD.15 | Misenite | K8H6(SO4)7 |
| 7.AD.20 | Letovicite | (NH4)3H(SO4)2 |
| 7.AD.25 | Thénardite | Na2SO4 |
| 7.AD.25 | Glauberite | Na2Ca(SO4)2 |
| 7.AD.30 | Metathénardite | Na2SO4 |
| 7.AD.30 | Anhydrite | CaSO4 |
| 7.AD.35 | Baryte | BaSO4 |
| 7.AD.35 | Celestine | SrSO4 |
| 7.AD.35 | Olsacherite | Pb2(Se6+O4)(SO4) |
| 7.AD.35 | Anglesite | PbSO4 |
| 7.AD.40 | Kalistrontite | K2Sr(SO4)2 |
| 7.AD.40 | Palmierite | K2Pb(SO4)2 |
| 7.AD.45 | Ivsite | Na3H(SO4)2 |
| 7.AD.55 | Markhininite | TlBi(SO4)2 |
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) | 44.8737% | 13,911 | 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 Arcanite
mindat.org URL:
https://www.mindat.org/min-314.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
Mineral Dealers:
References for Arcanite
Reference List:
Frondel, Clifford (1950) Notes and news: Notes on arcanite, ammonian aphthitalite and oxammite. American Mineralogist, 35 (7-8) 596-598
McGinnety, J. A. (1972) Redetermination of the structures of potassium sulphate and potassium chromate: the effect of electrostatic crystal forces upon observed bond lengths. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 28 (9) 2845-2852 doi:10.1107/s0567740872007022
Localities for Arcanite
Showing 44 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 | |
| [var: Taylorite (of Dana)] Bideaux |
| [var: Taylorite (of Dana)] Garske (n.d.) |
Botswana | |
| Handbook of Mineralogy |
Canada | |
| Abersteiner et al. (2018) |
| Shang (2000) |
Chile | |
| forum.amiminerals.org (2016) |
France | |
| Naze-Nancy Masalehdani et al. (2009) |
Germany | |
| Frenzel (1964) |
Iran | |
| Talbot et al. (2009) |
Italy | |
| D’Angeli et al. (2022) |
| Cavarretta et al. (1982) +2 other references |
| Toutain et al. (1995) |
Japan | |
| The Mineral Species of Japan (5th ed) |
Mexico | |
| Taran et al. (2000) +1 other reference |
Namibia | |
| Martini (1992) |
| Handbook of Mineralogy | |
| Handbook of Mineralogy |
| Handbook of Mineralogy |
| Handbook of Mineralogy | |
| Handbook of Mineralogy |
| Handbook of Mineralogy |
Peru | |
| [var: Taylorite (of Dana)] Taylor (1859) +1 other reference |
Poland | |
| Kruszewski et al. (2020) |
Russia | |
| Golovin et al. (2023) |
| Diederik Visser List #39 |
| Pavel M. Kartashov analytical data |
| Zubkova et al. (2018) +1 other reference | |
| Okrugin (2004) |
| Naumov et al. (2008) |
Saudi Arabia | |
| Saudi Geological Survey Open-File ... +1 other reference |
South Africa | |
| Handbook of Mineralogy |
| Giuliani et al. (2017) +1 other reference |
| Abersteiner et al. (2024) |
Spain | |
| Martínez-Arkarazo et al. (2007) |
| Benavente +2 other references |
Uganda | |
| Kasedde et al. (2014) |
USA | |
| Garvie (2016) |
| Eakle (1908) |
| Ingalls et al. (1908) |
| Northrop et al. (1996) |
| Hawley +5 other references |
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Yadovitaya fumarole, Second scoria cone, Northern Breakthrough, Great Fissure eruption, Tolbachik Volcanic field, Milkovsky District, Kamchatka Krai, Russia