Carobbiite
A valid IMA mineral species - grandfathered
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About Carobbiite
Guido Carobbi
Formula:
KF
Colour:
Colourless
Hardness:
2 - 2½
Specific Gravity:
2.505
Crystal System:
Isometric
Member of:
Name:
Named by Hugo Strunz in 1956 in honor of Guido Carobbi (20 October 1900, Pistoia, Tuscany, Italy - 16 January 1983, Florence, Tuscany, Italy), Professor at the Institute of Mineralogy and Geochemistry, University of Florence. Carobbi (1936 and 1940) twice described the new mineral potassium fluoride, but he did not name it. Carobbi found KF in some yellowish stalactites collected on February 7, 1934 at the bottom of Vesuvius crater in a lava cave of the Dec. 1933 intracrater effusion, located in the NE quarter. The mineral was described as tiny colorless cubic crystals in association with erythrosiderite, hieratite, and mercallite.
Unique Identifiers
Mindat ID:
908
Long-form identifier:
mindat:1:1:908:9
IMA Classification of Carobbiite
Approved, 'Grandfathered' (first described prior to 1959)
First published:
1936
Type description reference:
Classification of Carobbiite
3.AA.20
3 : HALIDES
A : Simple halides, without H2O
A : M:X = 1:1, 2:3, 3:5, etc.
3 : HALIDES
A : Simple halides, without H2O
A : M:X = 1:1, 2:3, 3:5, etc.
9.1.1.4
9 : NORMAL HALIDES
1 : AX
9 : NORMAL HALIDES
1 : AX
8.1.5
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
1 : Halides of the alkali metals and ammonium
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
1 : Halides 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 |
|---|---|---|
| Crb | 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 Carobbiite
Transparency:
Translucent
Colour:
Colourless
Hardness:
2 - 2½ on Mohs scale
Cleavage:
Distinct/Good
On {001}.
On {001}.
Density:
2.505 g/cm3 (Measured) 2.528 g/cm3 (Calculated)
Optical Data of Carobbiite
Type:
Isotropic
RI values:
n = 1.362
Surface Relief:
Very High (negative)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Chemistry of Carobbiite
Mindat Formula:
KF
Elements listed:
Crystallography of Carobbiite
Crystal System:
Isometric
Class (H-M):
m3m(4/m32/m) - Hexoctahedral
Space Group:
Fm3m
Setting:
Fm3m
Cell Parameters:
a = 5.34 Å
Unit Cell V:
152.27 ų (Calculated from Unit Cell)
Z:
4
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) |
|---|---|---|---|---|---|---|---|
| 0011330 | Carobbiite | Wyckoff R W G (1963) Second edition. Interscience Publishers, New York, New York rocksalt structure Crystal Structures 1 85-237 | 1963 | 0 | 293 | ||
| 0017895 | Carobbiite | Broch E, Oftedal I, Pabst A (1929) Neubestimmung der Gitterkonstanten von KF, CsCl und BaF2 _cod_database_code 1010978 Zeitschrift fur Physikalische Chemie 3 209-214 | 1929 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.675 Å | (100) |
| 1.8913 Å | (45) |
| 3.088 Å | (21) |
| 1.5443 Å | (10) |
| 1.1959 Å | (7) |
| 1.6125 Å | (6) |
| 1.3370 Å | (4) |
Comments:
Synthetic
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 45b : [Other oxidized fumarolic minerals] | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 50 : Coal and/or oil shale minerals | <0.36 |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 54 : Coal and other mine fire minerals (see also #51 and #56) |
Type Occurrence of Carobbiite
General Appearance of Type Material:
As minute cubic crystals, intermixed with other minerals
Place of Conservation of Type Material:
University of Florence, Florence, Italy, 1972/l.
Geological Setting of Type Material:
stalactites in cavities in lava.
Associated Minerals at Type Locality:
Synonyms of Carobbiite
Other Language Names for Carobbiite
Relationship of Carobbiite to other Species
Member of:
Other Members of Halite Group:
| Griceite | LiF | Iso. m3m(4/m32/m) : Fm3m |
| Halite | NaCl | Iso. m3m(4/m32/m) : Fm3m |
| Sylvite | KCl | Iso. m3m(4/m32/m) : Fm3m |
| Villiaumite | NaF | Iso. m3m(4/m32/m) : Fd3m |
Related Minerals - Strunz-mindat Grouping
| 3.AA. | Brontesite | (NH4)3PbCl5 |
| 3.AA.05 | Marshite | CuI |
| 3.AA.05 | Nantokite | CuCl |
| 3.AA.05 | 'UM1999-11:I:CuS' | Cu(I,S) |
| 3.AA.05 | Miersite | (Ag,Cu)I |
| 3.AA.10 | Tocornalite | (Ag,Hg)I (?) |
| 3.AA.10 | Iodargyrite | AgI |
| 3.AA.15 | Bromargyrite | AgBr |
| 3.AA.15 | Chlorargyrite | AgCl |
| 3.AA.20 | Sylvite | KCl |
| 3.AA.20 | Halite | NaCl |
| 3.AA.20 | Villiaumite | NaF |
| 3.AA.20 | Griceite | LiF |
| 3.AA.25 | 'UM1998-03-Cl:Tl' | TlCl |
| 3.AA.25 | Nataliyamalikite | TlI |
| 3.AA.25 | Lafossaite | Tl(Cl,Br) |
| 3.AA.25 | Salammoniac | NH4Cl |
| 3.AA.30 | Calomel | [Hg2]2+Cl2 |
| 3.AA.30 | Moschelite | [Hg2]2+I2 |
| 3.AA.30 | Kuzminite | HgBr |
| 3.AA.35 | Neighborite | NaMgF3 |
| 3.AA.35 | Parascandolaite | KMgF3 |
| 3.AA.40 | Javorieite | KFeCl3 |
| 3.AA.40 | Chlorocalcite | KCaCl3 |
| 3.AA.45 | Kolarite | PbTeCl2 |
| 3.AA.50 | Radhakrishnaite | PbTe3(Cl,S)2 |
| 3.AA.55 | Challacolloite | KPb2Cl5 |
| 3.AA.60 | Hephaistosite | TlPb2Cl5 |
| 3.AA.90 | Pseudocotunnite | K2PbCl4 |
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) | 67.2987% | 20,863 | 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
Notes:
Easily soluble in water.
Health Risks:
Although the mineral is not known to occur in sufficient natural abundances to be considered hazardous, be aware that the synthetic compound KF is poisonous (as are other water-soluble fluoride compounds such as NaF, occurring in nature as the mineral villiaumite) if ingested, inhaled or absorbed through the skin. However, lethal doses approach gram levels for humans. As is always good practice, minerals should be considered as chemicals, and so treated accordingly.
Internet Links for Carobbiite
mindat.org URL:
https://www.mindat.org/min-908.html
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References for Carobbiite
Reference List:
Localities for Carobbiite
Showing 6 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.
Costa Rica | |
| Rodríguez et al. (2017) |
Italy (TL) | |
| [Russo et al. (2004) |
| Rend.Soc.Min.Ital. (1956) +1 other reference | |
Japan | |
| Oana (1962) +1 other reference |
Poland | |
| Ł. Kruszewski (PXRD data) +1 other reference |
| Ł. Kruszewski PXRD data (to be published soon) +3 other references |
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Mount Vesuvius, Metropolitan City of Naples, Campania, Italy