Avogadrite
A valid IMA mineral species - grandfathered
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About Avogadrite
Lorenzo Romano Amedeo Carlo Avogadro di Quaregna (Quaregga) e di Cerreto
Formula:
(K,Cs)[BF4]
Colour:
Colourless to white, yellowish to reddish when impure, colourless in transmitted light
Specific Gravity:
2.9 (Calculated)
Crystal System:
Orthorhombic
Name:
Named after Amadeo Avogadro (9 August 1776, Turin, Italy – 9 July 1856, Turin, Italy), Professor of Physics at the University of Turin, Turin, Italy. Remembered for Avogadro's gas law and Avogadro's number.
This page provides mineralogical data about Avogadrite.
Unique Identifiers
Mindat ID:
438
Long-form identifier:
mindat:1:1:438:5
IMA Classification of Avogadrite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
KBF4
Classification of Avogadrite
3.CA.10
3 : HALIDES
C : Complex halides
A : Borofluorides
3 : HALIDES
C : Complex halides
A : Borofluorides
11.2.2.1
11 : HALIDE COMPLEXES
2 : AmBX4
11 : HALIDE COMPLEXES
2 : AmBX4
8.12.2
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
12 : Fluorborates (BF'4) and fluosilicates (SiF''6)
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
12 : Fluorborates (BF'4) and fluosilicates (SiF''6)
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 |
|---|---|---|
| Avg | 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 Avogadrite
Transparency:
Translucent
Colour:
Colourless to white, yellowish to reddish when impure, colourless in transmitted light
Density:
2.9 g/cm3 (Calculated)
Optical Data of Avogadrite
Type:
Biaxial (-)
RI values:
nα = 1.3239 nβ = 1.3245 nγ = 1.3247
2V:
Measured: 75° , Calculated: 58°
Max. Birefringence:
δ = 0.001
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
Dispersion:
r > v, strong
Chemistry of Avogadrite
Mindat Formula:
(K,Cs)[BF4]
Elements listed:
Crystallography of Avogadrite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pnma
Cell Parameters:
a = 8.6588 Å, b = 5.48 Å, c = 7.0299 Å
Ratio:
a:b:c = 1.58 : 1 : 1.283
Unit Cell V:
333.57 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Octagonal crystals, tabular to platy on {001}, may be elongated along [010] or [100].
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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CIF File Best | x | y | z | a | b | c
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Labels
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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) |
|---|---|---|---|---|---|---|---|
| 0012154 | Avogadrite | Clark M J R, Lynton H (1969) Crystal structures of potassium, ammonium, rubidium and cesium tetrafluoroborates Canadian Journal of Chemistry 47 2579-2586 | 1969 | synthetic | 0 | 293 | |
| 0009363 | Avogadrite | Brunton G (1969) The crystal structure of KBF4 Acta Crystallographica B25 2161-2162 |  | 1969 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.41 Å | (100) |
| 3.26 Å | (80) |
| 3.06 Å | (75) |
| 2.068 Å | (55) |
| 3.51 Å | (45) |
| 2.801 Å | (40) |
| 2.091 Å | (35) |
Comments:
X-ray data of synthetic K[BF4] (ICDD 16-378)
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 45b : [Other oxidized fumarolic minerals] |
Geological Setting:
Volcanic fumaroles
Type Occurrence of Avogadrite
General Appearance of Type Material:
minute octagonal crystals and dense crusts
Place of Conservation of Type Material:
Natural History Museum, Paris, France (No. 126.148)
Geological Setting of Type Material:
Sublimation products around volcanic fumaroles
Associated Minerals at Type Locality:
Other Language Names for Avogadrite
Dutch:Avogadriet
French:Avogadrite
German:Avogadrit
Avogadroit
Avogadroit
Norwegian:Avogadritt
Russian:Авогадрит
Spanish:Avogadrita
Common Associates
Associations Based on Photo Data:
| 7 photos of Avogadrite associated with Malladrite | Na2[SiF6] |
| 3 photos of Avogadrite associated with Ferruccite | Na[BF4] |
| 1 photo of Avogadrite associated with Knasibfite | K3Na4[SiF6]3[BF4] |
| 1 photo of Avogadrite associated with Verneite | Na2Ca3Al2F14 |
| 1 photo of Avogadrite associated with Sassolite | H3BO3 |
Related Minerals - Strunz-mindat Grouping
| 3.CA.05 | Ferruccite | Na[BF4] |
| 3.CA.10 | Barberiite | (NH4)[BF4] |
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) | 31.0543% | 9,627 | 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
Thermal Behaviour:
The mineral becomes cubic above 273°C.
Notes:
Slightly soluble in water.
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 Avogadrite
mindat.org URL:
https://www.mindat.org/min-438.html
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References for Avogadrite
Localities for Avogadrite
Showing 5 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 | |
| Russo et al. (2004) |
| Palache et al. (1951) |
| Palache et al. (1951) +2 other references | |
| Gramaccioli et al. (2007) |
Russia | |
| Anthony (1997) |
Quick NavTopAbout AvogadriteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence Other LanguagesCommon AssociatesStrunz-MindatRadioactivityOther InformationInternet Links References Localities Locality List
Vesuvius fumaroles, Metropolitan City of Naples, Campania, Italy