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Fersmite
A valid IMA mineral species - grandfathered
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About Fersmite
Post stamp with academic A. E. Fersman portrait.
Formula:
CaNb2O6
Previously given as (Ca,Ce,Na)(Nb,Ta,Ti)2(O,OH,F)6.
Colour:
Black, dark brown, lemon-yellow to yellow-brown
Lustre:
Sub-Vitreous, Resinous, Sub-Metallic
Hardness:
4 - 4½
Specific Gravity:
4.78 (Calculated)
Crystal System:
Orthorhombic
Member of:
Name:
Named in 1946 by Elsa Maximilianovna Bohnstedt-Kupletskaya and T. A. Burova in honour of academic Aleksandr Evgenievich Fersman (November 8, 1883 St. Petersburg, Russia - May 20, 1945 Sochi, Georgia), mineralogist, founder of the Fersman Mineralogical Museum in Moscow, Russia. The mineral fersmanite is also named after him.
Dimorph of:
Unique Identifiers
Mindat ID:
1539
Long-form identifier:
mindat:1:1:1539:0
IMA Classification of Fersmite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
CaNb5+2O6
Classification of Fersmite
4.DG.05
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
G : With large (+- medium-sized) cations; chains of edge-sharing octahedra
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
G : With large (+- medium-sized) cations; chains of edge-sharing octahedra
8.3.3.1
8 : MULTIPLE OXIDES CONTAINING NIOBIUM,TANTALUM OR TITANIUM
3 : AB2O6
8 : MULTIPLE OXIDES CONTAINING NIOBIUM,TANTALUM OR TITANIUM
3 : AB2O6
18.2.12
18 : Niobates and Tantalates
2 : Niobates and tantalates containing rare earths but not U
18 : Niobates and Tantalates
2 : Niobates and tantalates containing rare earths but not 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 |
|---|---|---|
| Fsm | 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 Fersmite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Fersmite
Sub-Vitreous, Resinous, Sub-Metallic
Transparency:
Translucent, Opaque
Colour:
Black, dark brown, lemon-yellow to yellow-brown
Streak:
Grayish brown
Hardness:
4 - 4½ on Mohs scale
Hardness:
VHN100=572 - 593 - Vickers
Tenacity:
Very brittle
Cleavage:
Distinct/Good
{100}
{100}
Parting:
present
Fracture:
Sub-Conchoidal
Density:
4.78 g/cm3 (Calculated)
Optical Data of Fersmite
Type:
Biaxial (+)
RI values:
nα = 2.07 nβ = 2.08 nγ = 2.19
2V:
Measured: 20° to 25°, Calculated: 36°
Max. Birefringence:
δ = 0.120
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:
Very High (positive)
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
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
r < v strong
Pleochroism:
Weak
Comments:
X = Y = pale greenish yellow to colorless; Z = dark greenish yellow to olive-yellow
Chemistry of Fersmite
Mindat Formula:
CaNb2O6
Previously given as (Ca,Ce,Na)(Nb,Ta,Ti)2(O,OH,F)6.
Previously given as (Ca,Ce,Na)(Nb,Ta,Ti)2(O,OH,F)6.
Element Weights:
Elements listed:
Crystallography of Fersmite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pbcn
Cell Parameters:
a = 14.926(4) Å, b = 5.752(4) Å, c = 5.204(4) Å
Ratio:
a:b:c = 2.595 : 1 : 0.905
Unit Cell V:
446.79 ų (Calculated from Unit Cell)
Z:
4
Morphology:
prismatic crystals
Comment:
commonly metamict
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
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) |
|---|---|---|---|---|---|---|---|
| 0012371 | Fersmite | Gurbanova O A, Rastsvetaeva R K, Kashaev A A, Smolin A S (2001) Refined crystal structure of TR-fersmite (TR = Ce) Crystallography Reports 46 194-195 | 2001 | Ust'-Biran deposit | 0 | 293 | |
| 0000196 | Fersmite | Cummings J P, Simonsen S H (1970) The crystal structure of calcium niobate (CaNb2O6) American Mineralogist 55 90-97 |  | 1970 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.049 Å | (100) |
| 3.762 Å | (21) |
| 1.527 Å | (15) |
| 2.493 Å | (14) |
| 1.183 Å | (13) |
| 1.211 Å | (11) |
| 1.967 Å | (10) |
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 | |
| 36 : Carbonatites, kimberlites, and related igneous rocks |
Geological Setting:
accessory mineral in nepheline syenites and carbonatites.
Type Occurrence of Fersmite
Place of Conservation of Type Material:
A.E. Fersman Mineralogical Museum, Academy of Sciences, Moscow, Russia, 44383, 44384
Other Language Names for Fersmite
Relationship of Fersmite to other Species
Member of:
Other Members of Euxenite Group:
| Euxenite-(Y) | (Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6 | Orth. mmm(2/m2/m2/m) : Pbcn |
| Kobeite-(Y) | (Y,U)(Ti,Nb)2(O,OH)6 (?) | Iso. |
| Loranskite-(Y) | (Y,Ce,Ca)ZrTaO6 (?) | |
| Tanteuxenite-(Y) | Y(Ta,Nb,Ti)2(O,OH)6 | Orth. mmm(2/m2/m2/m) : Pbcn |
| Uranopolycrase | (U4+,Y)(Ti,Nb)2O6 | Orth. mmm(2/m2/m2/m) : Pbcn |
| Yttrocrasite-(Y) | (Y,Th,Ca,U)(Ti,Fe)2(O,OH)6 | Amor. |
Common Associates
Associations Based on Photo Data:
| 6 photos of Fersmite associated with Microlite Group | A2-mTa2X6-wZ1-n |
| 5 photos of Fersmite associated with Albite | Na(AlSi3O8) |
| 4 photos of Fersmite associated with 'Uranmicrolite (of Hogarth 1977)' | (Ca,U,Na)2-x(Ta,Nb)2(O,OH)7 |
| 3 photos of Fersmite associated with Cassiterite | SnO2 |
| 3 photos of Fersmite associated with Svanbergite | SrAl3(PO4)(SO4)(OH)6 |
| 3 photos of Fersmite associated with Dolomite | CaMg(CO3)2 |
| 2 photos of Fersmite associated with Pyrite | FeS2 |
| 2 photos of Fersmite associated with Lueshite | NaNbO3 |
| 1 photo of Fersmite associated with Hydroxycalciopyrochlore | (Ca,Na,U,◻)2(Nb,Ti)2O6(OH) |
| 1 photo of Fersmite associated with Ancylite-(Ce) | CeSr(CO3)2(OH) · H2O |
Related Minerals - Strunz-mindat Grouping
| 4.DG.05 | Uranopolycrase | (U4+,Y)(Ti,Nb)2O6 |
| 4.DG.05 | Yttrocrasite-(Y) | (Y,Th,Ca,U)(Ti,Fe)2(O,OH)6 |
| 4.DG.05 | Tanteuxenite-(Y) | Y(Ta,Nb,Ti)2(O,OH)6 |
| 4.DG.05 | Loranskite-(Y) | (Y,Ce,Ca)ZrTaO6 (?) |
| 4.DG.05 | Euxenite-(Y) | (Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6 |
| 4.DG.05 | Kobeite-(Y) | (Y,U)(Ti,Nb)2(O,OH)6 (?) |
| 4.DG.10 | Yttrotantalite-(Y) | (Y,U,Fe2+)(Ta,Nb)(O,OH)4 |
| 4.DG.10 | Clinofergusonite-(Y) | YNbO4 |
| 4.DG.10 | Clinofergusonite-(Nd) | (Nd,Ce)NbO4 |
| 4.DG.10 | Clinofergusonite-(Ce) | CeNbO4 |
| 4.DG.15 | Foordite | Sn2+Nb2O6 |
| 4.DG.15 | Thoreaulite | Sn2+Ta2O6 |
| 4.DG.20 | Raspite | Pb(WO4) |
Fluorescence of Fersmite
Fluoresces yellow-green to bluish green under SW and LW UV; light blue cathodoluminescence
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 Fersmite
mindat.org URL:
https://www.mindat.org/min-1539.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 Fersmite
Localities for Fersmite
Showing 140 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.
Australia | |
| Johns-Mead et al. (2024) |
| Fetherston (2004) |
Austria | |
| Postl et al. (1987) |
| Mali (2004) |
| Mali (2004) | |
Brazil | |
| Gomes et al. (2023) |
| Gomes et al. (2023) | |
| Beurlen et al. (2008) |
| Beurlen +4 other references |
| COMIN-CHIARAMONTI et al. (2002) |
Bulgaria | |
| Georgieva et al. (2023) |
Canada | |
| GJ Simandl (1991) +2 other references |
| Chudy T et al. (2014) |
| George J. Simandl (2001) | |
| Blue River Carbonatites et al. (http://www.commerceresources.com/i/pdf/05-BCGOVRREPORT.pdf) | |
| Berger et al. (2009) | |
| Taseko |
| Paul (1984) +1 other reference |
| Bannatyne (1985) |
| Camacho et al. (2014) |
| Papoutsa et al. (2013) |
| McLaughlin (1990) |
| Savard (2019) |
| D. Turner and L.A. Groat (2010) +1 other reference |
China | |
| Shi Li (1980) +4 other references |
| Yi-Li et al. (2023) +3 other references |
| Zhang Peishan et al. (1996) +2 other references | |
| Yang et al. (2026) | |
| Xie et al. (2026) | |
| Zhang Peishan et al. (1996) | |
| Wu et al. (2023) +1 other reference |
| Xue et al. (2021) |
| Xue et al. (2021) | |
| Lin et al. (1995) |
| Wang et al. (2024) |
Czech Republic | |
| Novak et al. (2010) +2 other references |
| Ddolníček Z et al. (2020) |
| Novák | |
| Sejkora +2 other references | |
| Sejkora et al. (2020) |
| Novák et al. (1996) |
| Výravský et al. (2017) |
DR Congo | |
| www.handbookofmineralogy.com (2012) +1 other reference |
| Voloshin A.V. (1988) |
France | |
| MONCHOUX P. et al. (2006) |
Germany | |
| Hentschel (1990) |
| Hentschel (1990) | |
| Hentschel (1990) |
| Hentschel (1990) |
Greenland | |
| Petersen (2001) |
| Bohse et al. (2001) | |
India | |
| Singh et al. (2017) |
| Acharya et al. (1982) |
| Chakrabarty et al. (2018) |
Italy | |
| Guastoni et al. (2010) |
| Grill (1935) |
| Sergio Varvello collection | |
| Piccoli et al. (2007) |
| Preite et al. (2010) |
| Mattioli (1979 a) +8 other references |
| Piccoli et al. (2007) +1 other reference | |
| Callegari A. (2002) | |
| Albertini (2011) | |
| Gamboni et al. (2001) |
Kazakhstan | |
| Stepanov et al. (2012) |
Madagascar | |
| Pezzotta (1999) |
| De Vito et al. (2006) | |
Mongolia | |
| Pavel M. Kartashov (n.d.) +1 other reference |
| Kartashov P.M. et al. (Mongolian Altai) |
| Pavel M. Kartashov (n.d.) +1 other reference | |
Mozambique | |
| Moiana (2010) |
North Korea | |
| Kim et al. (2023) |
Norway | |
| Larsen (2001) |
| Nordrum (2008) +1 other reference |
| Husdal (2023) |
| Pršek et al. (2010) |
| Raade (1993) |
| Neumann (1985) |
| Larsen (2021) |
Poland | |
| PIECZKA et al. 2010: Nb-Ta minerals in ... |
| SZUSZKIEWICZ et al. (2013) +1 other reference | |
| Evans et al. (2018) +1 other reference |
| Pieczka et al. (2024) +1 other reference |
| Pieczka (2006) +3 other references |
Romania | |
| Pál Molnár (2000) |
| Hirtopanu et al. (2013) |
| Săbău (2010) |
Russia | |
| Makagonov et al. (2017) |
| Sorokina et al. (2019) |
| Chakhmouradian et al. (2015) | |
| Nedosekova (2007) +1 other reference | |
| Popova et al. (2018) | |
| Pekov (1998) |
| webmineral.ru (2016) | |
| Попова et al. (2019) |
| Chakhmouradian et al. (2015) |
| Chakhmouradian et al. (1999) |
| Vital'Evna (2021) |
| Igor.V. Pekov (2008) |
| Zakharov et al. (2022) | |
| Chakhmouradian et al. (2015) |
Slovakia | |
| Uher |
| Huraiová et al. (2019) |
| Uher P. et al. (2018) |
| Uher et al. (Považský Inovec) |
| Uher P. +1 other reference | |
South Africa | |
| Cairncross et al. (1995) |
| VERWOERD (1986) |
South Korea | |
| Pavel M. Kartashov (n.d.) |
Spain | |
| Ковальчук et al. (2014) +1 other reference |
| Casillas et al. (2011) | |
| Dill et al. (2023) |
Sri Lanka | |
| Pavel M. Kartashov analytical data (2011) +1 other reference |
Sweden | |
| Sandström et al. (2010) |
| Sandström et al. (2010) | |
| Sandström et al. (2010) | |
Tajikistan | |
| Pautov et al. (2022) |
Tanzania | |
| Chakhmouradian et al. (2015) |
UK | |
| Knorring et al. (1984) |
USA | |
| Philpotts et al. (1998) |
| Philpotts et al. (1998) |
| Howard (1987) |
| Barwood (1989) |
| Min News (2000) | |
| Rocks and Mineral: 1998: 168 & 178 +1 other reference |
| Foord et al. (1978) | |
| Eckel et al. (1997) |
| USGS Prof Paper 649 +1 other reference | |
| Eckel et al. (1997) |
| McIntosh et al. (2026) |
| McIntosh et al. (2026) | |
| Wang et al. (2023) +2 other references |
| Buchholz et al. (2014) |
| Am Min (1959) +1 other reference |
| Gammons et al. (2024) |
| Heinrich et al. (1961) |
| Nashua Min. Soc. Display Cat. |
| Chris O'Neill and Travis Olds |
| Rocks and Minerals +2 other references |
| a classic locality revisited. The Canadian Mineralogist (2) +1 other reference |
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Alpe Rosso, Orcesco, Druogno, Verbano-Cusio-Ossola Province, Piedmont, Italy