Bütschliite
A valid IMA mineral species - grandfathered
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About Bütschliite
Johann Adam Otto Bütschli
Formula:
K2Ca(CO3)2
Colour:
Grayish yellow, brownish gray, may be pale green
Specific Gravity:
2.607 (Calculated)
Crystal System:
Trigonal
Name:
Named after Johann Adam Otto Bütschli (1848-1920), Heidelberg, Germany, who prepared the artificial compound.
Co-Type Localities:
Dimorph of:
The low-temperature polymorph of fairchildite.
The transformation between bütschliite and fairchildite was studied by Kahlenberg et al. (2025).
Previously considered a poorly studied material that should probably not be afforded species status.
The transformation between bütschliite and fairchildite was studied by Kahlenberg et al. (2025).
Previously considered a poorly studied material that should probably not be afforded species status.
Name Encoding
ASCII-7:
Butschliite
Unique Identifiers
Mindat ID:
821
Long-form identifier:
mindat:1:1:821:1
IMA Classification of Bütschliite
Approved, 'Grandfathered' (first described prior to 1959)
First published:
1947
Classification of Bütschliite
5.AC.15
5 : CARBONATES (NITRATES)
A : Carbonates without additional anions, without H2O
C : Alkali and alkali-earth carbonates
5 : CARBONATES (NITRATES)
A : Carbonates without additional anions, without H2O
C : Alkali and alkali-earth carbonates
Dana 7th ed.:
14.3.1.1
14.3.1.1
14 : ANHYDROUS NORMAL CARBONATES
3 : A2B(XO3)2
14 : ANHYDROUS NORMAL CARBONATES
3 : A2B(XO3)2
11.1.17
11 : Carbonates
1 : Carbonates of the alkali metals and ammonium
11 : Carbonates
1 : Carbonates 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 |
|---|---|---|
| Büt | 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 Bütschliite
Transparency:
Translucent
Colour:
Grayish yellow, brownish gray, may be pale green
Streak:
(not reported)
Cleavage:
Distinct/Good
Good (?) on {0001}
Good (?) on {0001}
Density:
2.607 g/cm3 (Calculated)
Optical Data of Bütschliite
Type:
Uniaxial
RI values:
nω = 1.595 nε = 1.455
Max. Birefringence:
δ = 0.140
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
Chemistry of Bütschliite
Mindat Formula:
K2Ca(CO3)2
Element Weights:
Elements listed:
Crystallography of Bütschliite
Crystal System:
Trigonal
Class (H-M):
3m(32/m) - Hexagonal Scalenohedral
Space Group:
R3m
Cell Parameters:
a = 5.3822(4) Å, c = 18.156(2) Å
Ratio:
a:c = 1 : 3.373
Unit Cell V:
455.48 ų (Calculated from Unit Cell)
Z:
3
Morphology:
Microscopic barrel-shaped crystals elongated [0001], earthy to porcellaneous masses.
Comment:
On synthetic; at 6 GPa transforms to monoclinic (C2/m) phase (Zeff et al. 2024)
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 0.933 Å | (20) |
| 1.044 Å | (20) |
| 1.614 Å | (20) |
| 1.69 Å | (20) |
| 2.07 Å | (10) |
| 2.69 Å | (10) |
| 2.86 Å | (100) |
| 3.02 Å | (30) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 29 : Lightning-generated minerals | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 53 : Other minerals with taphonomic origins | <0.4 |
Type Occurrence of Bütschliite
Co-Type Localities:
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA, 105675, 105676.
Geological Setting of Type Material:
Clinkers formed by the fusion of wood ash in partly burned trees.
Associated Minerals at Type Locality:
Synonyms of Bütschliite
Other Language Names for Bütschliite
Related Minerals - Strunz-mindat Grouping
| 5.AC.05 | Eitelite | Na2Mg(CO3)2 |
| 5.AC.10 | Zemkorite | Na2Ca(CO3)2 |
| 5.AC.10 | Nyerereite | Na2Ca(CO3)2 |
| 5.AC.20 | Fairchildite | K2Ca(CO3)2 |
| 5.AC.25 | Shortite | Na2Ca2(CO3)3 |
| 5.AC.30 | Burbankite | (Na,Ca)3(Sr,Ba,Ce)3(CO3)5 |
| 5.AC.30 | Calcioburbankite | Na3(Ca,REE,Sr)3(CO3)5 |
| 5.AC.30 | Sanrománite | Na2CaPb3[CO3]5 |
| 5.AC.30 | Khanneshite | (Na,Ca)3(Ba,Sr,Ce,Ca)3(CO3)5 |
| 5.AC.30 | Lishiite | (Ca2◻)Sr3(CO3)5 |
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) | 32.8154% | 10,173 | 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 Bütschliite
mindat.org URL:
https://www.mindat.org/min-821.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 Bütschliite
Reference List:
Milton, Charles, Axelrod, Joseph (1947) Fused wood-ash stones: Fairchildite (n.sp.) K2CO3·CaCO3, buetschliite (n.sp.) 3K2CO3·2CaCO3·6H2O and calcite, CaCO3, their essential components. American Mineralogist, 32 (11-12) 607-624
Dawson, Kenneth Ralph; Sabina, Ann P. (1958) A Canadian occurrence of fairchildite and buetschliite [Ontario]. The Canadian Mineralogist, 6 (2). 290-291
Pabst, Adolf (1974) Synthesis, properties, and structure of K2Ca(CO3)2, buetschliite. American Mineralogist, 59 (3-4) 353-358
Kahlenberg, Volker, Braun, Doris E., Schmidt, Wolfgang, Liu, Hang, Leiting, Sebastian, Weidenthaler, Claudia (2025) Mechanochemical synthesis and transformation of the polymorphic double carbonates fairchildite and buetschliite, (K2Ca(CO3)2): an in situ X-ray powder diffraction study. RSC Mechanochemistry, 2 (1). 152-158 doi:10.1039/d4mr00093e
Localities for Bütschliite
Showing 14 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.
Brazil | |
| Bermanec et al. (2011) +1 other reference |
| Scholz et al. (2014) | |
Canada | |
| Mineralogical Society of America - ... +1 other reference |
| Mineralogical Society of America - ... |
| Traill (1983) | |
Poland | |
| Kruszewski et al. (2020) |
Russia | |
| Logvinova et al. (2019) |
South Africa | |
| Abersteiner et al. (2024) |
USA | |
| Milton (1944) +3 other references |
| Milton et al. (1947) | |
| Garvie (2016) |
| Anthony et al. (2016) |
| ID by PXRD (madrone) |
| Dietrich (1971) |
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Gold Hill Mining District, Jackson County, Oregon, USA