Franconite
A valid IMA mineral species
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About Franconite
Formula:
Na(Nb2O5)(OH) · 3H2O
Colour:
White, colorless, grayish blue.
Lustre:
Adamantine, Vitreous, Silky
Hardness:
4
Specific Gravity:
2.72
Crystal System:
Monoclinic
Member of:
Name:
Named by J.L. Jambor, A.P. Sabina, A.C. Roberts, M. Bonardi, R.A. Ramik, and B.D. Sturman in 1984 for the type locality of Francon Quarry, Canada.
Type Locality:
This page provides mineralogical data about Franconite.
Unique Identifiers
Mindat ID:
1595
Long-form identifier:
mindat:1:1:1595:6
Similar Names
| Francolite | A synonym of 'Carbonate-rich Fluorapatite' |
| Franquenite | A synonym of Slavíkite |
IMA Classification of Franconite
Approved
IMA Formula:
NaNb5+2O5(OH)·3H2O
Approval year:
1981
First published:
1984
Classification of Franconite
4.FM.15
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
M : Hydroxides with H2O +- (OH); unclassified
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
M : Hydroxides with H2O +- (OH); unclassified
8.6.1.1
8 : MULTIPLE OXIDES CONTAINING NIOBIUM,TANTALUM OR TITANIUM
6 : (AB)6O11·nH2O
8 : MULTIPLE OXIDES CONTAINING NIOBIUM,TANTALUM OR TITANIUM
6 : (AB)6O11·nH2O
18.1.4
18 : Niobates and Tantalates
1 : Niobates and tantalates containing neither rare earths nor U
18 : Niobates and Tantalates
1 : Niobates and tantalates containing neither rare earths nor U
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 |
|---|---|---|
| Fra | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Franconite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Franconite
Adamantine, Vitreous, Silky
Transparency:
Transparent
Comment:
silky on fractures
Colour:
White, colorless, grayish blue.
Streak:
White
Hardness:
4 on Mohs scale
Cleavage:
None Observed
Parting:
: Basal, parting.
Density:
2.72(1) g/cm3 (Measured) 2.71 g/cm3 (Calculated)
Optical Data of Franconite
Type:
Biaxial (-)
RI values:
nα = 1.72 nβ = 1.78 nγ = 1.79
2V:
Measured: 35° (5)
Max. Birefringence:
δ = 0.070
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 moderate
Chemistry of Franconite
Mindat Formula:
Na(Nb2O5)(OH) · 3H2O
Element Weights:
Elements listed:
Crystallography of Franconite
Crystal System:
Monoclinic
Cell Parameters:
a = 22.21 Å, b = 12.87 Å, c = 6.35 Å
β = 92.24°
β = 92.24°
Ratio:
a:b:c = 1.726 : 1 : 0.493
Unit Cell V:
1,813.71 ų (Calculated from Unit Cell)
Z:
4
Comment:
Point Group: n.d.; Space Group: n.d.
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) |
|---|---|---|---|---|---|---|---|
| 0020435 | Franconite | Haring M M M, McDonald A M (2014) Franconite, NaNb2O5(OH)*3H2O: structure determination and the role of H bonding, with comments on the crystal chemistry of franconite-related minerals Mineralogical Magazine 78 591-607 | 2014 | Poudrette quarry, Quebec, Canada | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 11.0 Å | (100) |
| 5.55 Å | (70) |
| 4.73 Å | (60) |
| 3.18 Å | (60) |
| 4.21 Å | (50) |
| 3.21 Å | (50) |
| 2.626 Å | (50) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 35 : Ultra-alkali and agpaitic igneous rocks |
Type Occurrence of Franconite
General Appearance of Type Material:
White globules consists of radiating bladed crystals.
Place of Conservation of Type Material:
Geological Survey of Canada, Ottawa, 62094, 63748–63750.
Royal Ontario Museum, Toronto, Canada, M39041.
Royal Ontario Museum, Toronto, Canada, M39041.
Associated Minerals at Type Locality:
Synonyms of Franconite
Other Language Names for Franconite
Relationship of Franconite to other Species
Member of:
Other Members of Franconite Group:
| Hochelagaite | (Ca,Na,Sr)(Nb,Ti,Si,Al)4O11 · 8H2O | Mon. |
| Ternovite | (Mg,Ca)Nb4O11 · nH2O | Mon. |
Common Associates
Associations Based on Photo Data:
| 33 photos of Franconite associated with Albite | Na(AlSi3O8) |
| 33 photos of Franconite associated with Aegirine | NaFe3+Si2O6 |
| 27 photos of Franconite associated with Microcline | K(AlSi3O8) |
| 25 photos of Franconite associated with Thomasclarkite-(Y) | (Na,Ce)(Y,REE)(HCO3)(OH)3 · 4H2O |
| 21 photos of Franconite associated with Adamsite-(Y) | NaY[CO3]2 · 6H2O |
| 15 photos of Franconite associated with Siderite | FeCO3 |
| 13 photos of Franconite associated with Gaidonnayite | Na2Zr(Si3O9) · 2H2O |
| 13 photos of Franconite associated with Niobokupletskite | K2NaMn2+7(NbTi)[Si4O12]2O2(OH)4O |
| 11 photos of Franconite associated with Rhodochrosite | MnCO3 |
| 9 photos of Franconite associated with Weloganite | Na2Sr3Zr(CO3)6 · 3H2O |
Related Minerals - Strunz-mindat Grouping
| 4.FM. | Charleshatchettite | CaNb4O10(OH)2 · 8H2O |
| 4.FM.15 | Hochelagaite | (Ca,Na,Sr)(Nb,Ti,Si,Al)4O11 · 8H2O |
| 4.FM.15 | Ternovite | (Mg,Ca)Nb4O11 · nH2O |
| 4.FM.25 | Belyankinite | Ca1-2(Ti,Zr,Nb)5O12 · 9H2O (?) |
| 4.FM.25 | Gerasimovskite | Mn2+(Nb,Ti)5O12 · 9H2O (?) |
| 4.FM.25 | Manganbelyankinite | Mn2+(Ti,Nb)5O12 · 9H2O |
| 4.FM.30 | Silhydrite | Si3O6 · H2O |
| 4.FM.35 | Cuzticite | Fe3+2(TeO6) · 3H2O |
| 4.FM.50 | Qatranaite | CaZn2(OH)6(H2O)2 |
| 4.FM.55 | 'Hydroplumbite' | 3PbO · H2O |
Fluorescence of Franconite
fluoresces pale yellow under LW UV, more intensely under SW UV.
Other Information
Notes:
Does not effervesce in HCl, and is not readily consumed by HCl.
Special Storage/
Display Requirements:
Display Requirements:
Dehydrates, reversibly
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 Franconite
mindat.org URL:
https://www.mindat.org/min-1595.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Franconite
Reference List:
Jambor, John L., Sabina, A. P., Roberts, Andrew C., Bonardi, M., Ramik, R. A., Sturman, B. D. (1984) Franconite, a new hydrated Na-Nb oxide mineral from Montreal Island, Quebec. The Canadian Mineralogist, 22 (2) 239-243
Localities for Franconite
Showing 7 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.
Canada | |
| Horváth et al. (1990) +1 other reference |
| Horváth et al. (1998) |
| Horváth et al. (1998) | |
| 176-178. +3 other references |
Russia | |
| Nikandrov (1989) +1 other reference |
| Pekov et al. (2004) |
| Subbotin et al. (1997) +2 other references |
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Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada