Fontanite
A valid IMA mineral species
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About Fontanite
François Fontan
Formula:
Ca(UO2)3(CO3)4 · 3H2O
Colour:
Bright yellow
Lustre:
Vitreous
Hardness:
3
Specific Gravity:
4.10
Crystal System:
Monoclinic
Name:
Named by Michel Deliens and Paul Piret in 1992 in honor of François Fontan (1942, Toulouse, France - July 2007), mineralogist and expert on pegmatites at the University of Toulouse, France.
Type Locality:
This page provides mineralogical data about Fontanite.
Unique Identifiers
Mindat ID:
1580
Long-form identifier:
mindat:1:1:1580:2
Similar Names
| Montanite | A valid IMA mineral species | Bi2(TeO6) · nH2O |
IMA Classification of Fontanite
Approved
IMA Formula:
Ca(UO2)3(CO3)2O2 · 6H2O
Approval year:
1991
First published:
1992
Classification of Fontanite
5.EC.05
5 : CARBONATES (NITRATES)
E : Uranyl Carbonates
C : UO2:CO3 < 1:1 - 1:2
5 : CARBONATES (NITRATES)
E : Uranyl Carbonates
C : UO2:CO3 < 1:1 - 1:2
15.3.6.1
15 : HYDRATED NORMAL CARBONATES
3 : AmBn(XO3)p·xH2O, with (m+n):p = 1:1
15 : HYDRATED NORMAL CARBONATES
3 : AmBn(XO3)p·xH2O, with (m+n):p = 1:1
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 |
|---|---|---|
| Ftn | 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 Fontanite
Vitreous
Transparency:
Transparent
Colour:
Bright yellow
Streak:
White
Hardness:
3 on Mohs scale
Cleavage:
Distinct/Good
Good on {100}, {010}, and {001}.
Good on {100}, {010}, and {001}.
Density:
4.10 g/cm3 (Measured) 3.984 g/cm3 (Calculated)
Comment:
Measured >4.10
Optical Data of Fontanite
Type:
Biaxial (-)
RI values:
nα = 1.603 nβ = 1.690 nγ = 1.710
2V:
Measured: 50° , Calculated: 48°
Max. Birefringence:
δ = 0.107
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
Chemistry of Fontanite
Mindat Formula:
Ca(UO2)3(CO3)4 · 3H2O
Element Weights:
Crystallography of Fontanite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 6.968(3) Å, b = 17.276(7) Å, c = 15.377(6) Å
β = 90.064(6)°
β = 90.064(6)°
Ratio:
a:b:c = 0.403 : 1 : 0.89
Unit Cell V:
1,851.07 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Rectangular lath-shaped crystals, elongate [001], platy (010), showing {100} and {010}.
Comment:
Space Group: P21/n.
Crystal Structure
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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) |
|---|---|---|---|---|---|---|---|
| 0003131 | Fontanite | Hughes K-A, Burns P C (2003) A new uranyl carbonate sheet in the crystal structure of fontanite, Ca[(UO2)3(CO3)2O2](H2O)6 American Mineralogist 88 962-966 |  | 2003 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 8.55 Å | (100) |
| 6.94 Å | (50) |
| 4.11 Å | (60) |
| 3.723 Å | (60) |
| 3.460 Å | (50) |
| 3.211 Å | (40) |
| 2.772 Å | (70) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47c : [Carbonates, phosphates, borates, nitrates] | |
| 47f : [Uranyl (U⁶⁺) minerals] |
Type Occurrence of Fontanite
Place of Conservation of Type Material:
Royal Belgian Institute of Natural Sciences, Brussels, Belgium, RC4216.
Geological Setting of Type Material:
Oxidized zone of a uranium deposit.
Associated Minerals at Type Locality:
Synonyms of Fontanite
Other Language Names for Fontanite
Common Associates
Associations Based on Photo Data:
| 4 photos of Fontanite associated with Uranophane | Ca(UO2)2(SiO3OH)2 · 5H2O |
Related Minerals - Strunz-mindat Grouping
| 5.EC.10 | Zellerite | Ca(UO2)(CO3)2 · 5H2O |
| 5.EC.10 | Metazellerite | Ca(UO2)(CO3)2 · 3H2O |
| 5.EC.15 | Ewingite | Mg8Ca8(UO2)24(CO3)30O4(OH)12(H2O)138 |
| 5.EC.20 | Meyrowitzite | Ca(UO2)(CO3)2 · 5H2O |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 62.4069% | 15,601,725 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 0.0000% | 0 | 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
Fluorescence of Fontanite
Light green under long-wave ultraviolet light.
Other Information
Notes:
radioactive
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 Fontanite
mindat.org URL:
https://www.mindat.org/min-1580.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Fontanite
Reference List:
Deliens, Michel, Piret, Paul (1992) La fontanite, carbonate hydraté d' uranyle et de calcium, nouvelle espèce minérale de Rabejac, Hérault, France. European Journal of Mineralogy, 4 (6) 1271-1274 doi:10.1127/ejm/4/6/1271
Burns, Peter C., Hughes, Karrie-Ann, Burns, Peter C. (2003) A new uranyl carbonate sheet in the crystal structure of fontanite, Ca[(UO2)3(CO3)2O2](H2O)6. American Mineralogist, 88 (7) 962-966 doi:10.2138/am-2003-0703
Burns, Peter C. (2005) U6+ minerals and inorganic compounds: insights into an expanded structural hierarchy of crystal structures. The Canadian Mineralogist, 43 (6) 1839-1894 doi:10.2113/gscanmin.43.6.1839
virtualcollections.naturalsciences.be (n.d.) http://virtualcollections.naturalsciences.be/virtual-collections/geology/mineralogy/mineralogy-types/fontanite
Localities for Fontanite
Showing 3 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.
Czech Republic | |
| Pauliš P. et al. (Kutna Hora, issue 2) |
France (TL) | |
| [European Journal of Mineralogy (1992) +2 other references |
Greece | |
| Rieck et al. (2022) |
Quick NavTopAbout FontaniteUnique IdentifiersSimilar NamesIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesCommon AssociatesStrunz-MindatRadioactivityFluorescence Other InformationInternet Links References Localities Locality List
Rabejac Est, Le Puech, Lodève, Hérault, Occitanie, France