Sekaninaite
A valid IMA mineral species
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About Sekaninaite
Josef Sekanina
Formula:
Fe2+2Al4Si5O18
Colour:
grayish-blue to bluish-violet
Lustre:
Vitreous
Hardness:
7 - 7½
Specific Gravity:
2.76 - 2.77
Crystal System:
Orthorhombic
Member of:
Name:
Named in honour of Josef Sekanina (4 September 1901, Knínice u Boskovic, Czech Republic - 28 November 1986, Letovice, Czech Republic), Czech mineralogist who first found the mineral.
Type Locality:
Dimorph of:
Unique Identifiers
Mindat ID:
3609
Long-form identifier:
mindat:1:1:3609:8
IMA Classification of Sekaninaite
Approved
IMA Formula:
Fe2+2Al3(AlSi5)O18
Approval year:
1967
First published:
1975
Classification of Sekaninaite
9.CJ.10
9 : SILICATES (Germanates)
C : Cyclosilicates
J : [Si6O18]12- 6-membered single rings (sechser-Einfachringe), without insular complex anions
9 : SILICATES (Germanates)
C : Cyclosilicates
J : [Si6O18]12- 6-membered single rings (sechser-Einfachringe), without insular complex anions
61.2.1.2
61 : CYCLOSILICATES Six-Membered Rings
2 : Six-Membered Rings with Al substituted rings
61 : CYCLOSILICATES Six-Membered Rings
2 : Six-Membered Rings with Al substituted rings
16.19.3
16 : Silicates Containing Aluminum and other Metals
19 : Aluminosilicates of Fe and Mg
16 : Silicates Containing Aluminum and other Metals
19 : Aluminosilicates of Fe and Mg
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Skn | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Skn | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Physical Properties of Sekaninaite
Vitreous
Transparency:
Transparent, Translucent
Colour:
Grayish-blue to bluish-violet
Hardness:
7 - 7½ on Mohs scale
Cleavage:
Imperfect/Fair
{100} imperfect
{100} imperfect
Parting:
{001}
Density:
2.76 - 2.77 g/cm3 (Measured) 2.78 g/cm3 (Calculated)
Optical Data of Sekaninaite
Type:
Biaxial (-)
RI values:
nα = 1.561 nβ = 1.572 nγ = 1.576
2V:
Measured: 66° , Calculated: 60°
Max. Birefringence:
δ = 0.015
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 (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:
weak
Pleochroism:
Visible
Comments:
X = colorless; Y = blue; Z = pale blue.
Chemistry of Sekaninaite
Mindat Formula:
Fe2+2Al4Si5O18
Element Weights:
Elements listed:
Common Impurities:
Ti,Mn,Ca,Na,K,H2O
Crystallography of Sekaninaite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Cccm
Setting:
Cccm
Cell Parameters:
a = 17.230(5) Å, b = 9.835(3) Å, c = 9.314(3) Å
Ratio:
a:b:c = 1.752 : 1 : 0.947
Unit Cell V:
1,578.32 ų (Calculated from Unit Cell)
Z:
4
Morphology:
poorly developed crystals, to 70 cm.
Twinning:
Type material - usually twinned on {110} and {310}, simulating hexagonal symmetry.
Crystal Structure
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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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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) |
|---|---|---|---|---|---|---|---|
| 0000709 | Sekaninaite | Hochella M F, Brown G E, Ross F K, Gibbs G V (1979) High-temperature crystal chemistry of hydrous Mg- and Fe-cordierite American Mineralogist 64 337-351 |  | 1979 | 0 | 297 | |
| 0000710 | Sekaninaite | Hochella M F, Brown G E, Ross F K, Gibbs G V (1979) High-temperature crystal chemistry of hydrous Mg- and Fe-cordierite American Mineralogist 64 337-351 | | 1979 | 0 | 648 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 8.583 Å | (100) |
| 3.386 Å | (100) |
| 3.376 Å | (100) |
| 4.081 Å | (83) |
| 3.076 Å | (74) |
| 3.143 Å | (64) |
| 3.043 Å | (57) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites | |
| Stage 5: Initiation of plate tectonics | <3.5-2.5 |
| 41 : Mantle metasomatism |
Type Occurrence of Sekaninaite
Place of Conservation of Type Material:
Moravian Museum, Brno, Czech Republic, A6108.
Associated Minerals at Type Locality:
Synonyms of Sekaninaite
Other Language Names for Sekaninaite
Relationship of Sekaninaite to other Species
Member of:
Other Members of Cordierite Group:
| Cordierite | Mg2Al4Si5O18 | Orth. mmm(2/m2/m2/m) : Cccm |
| Ferroindialite | (Fe2+,Mg)2Al4Si5O18 | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Indialite | Mg2Al3(AlSi5O18) | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Sachanbińskiite | NaMn4(Al5Be)(AlSi5O18)2 · 2H2O | Orth. mmm(2/m2/m2/m) : Cccm |
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 2 photos of Sekaninaite associated with Microcline | K(AlSi3O8) |
| 1 photo of Sekaninaite associated with Orthoclase | K(AlSi3O8) |
Related Minerals - Strunz-mindat Grouping
| 9.CJ. | Zolotarevite | Na5Zr[Si6O15(OH)3] · 3H2O |
| 9.CJ. | 'Avdeevite' | NaAl4(Be5Li)(Si6O18)2(H2O)1-2 |
| 9.CJ. | 'Beryllocordierite-Na' | NaMg4(Al5Be)(AlSi5O18)2 · 2H2O |
| 9.CJ. | Sachanbińskiite | NaMn4(Al5Be)(AlSi5O18)2 · 2H2O |
| 9.CJ. | Nakkaalaaqite | K2[Na3Ca]LiCa2Ti2Be4Si12O38 |
| 9.CJ.05 | Johnkoivulaite-(Cs) | Cs[Be2B]Mg2Si6O18 |
| 9.CJ.05 | Beryl | Be3Al2(Si6O18) |
| 9.CJ.05 | Bazzite | Be3Sc2(Si6O18) |
| 9.CJ.05 | Ferroindialite | (Fe2+,Mg)2Al4Si5O18 |
| 9.CJ.05 va | 'Vorobyevite' | Be3Al2(Si6O18) |
| 9.CJ.05 | Stoppaniite | Be3Fe3+2(Si6O18) · H2O |
| 9.CJ.05 | Indialite | Mg2Al3(AlSi5O18) |
| 9.CJ.10 | Cordierite | Mg2Al4Si5O18 |
| 9.CJ.15a | Zirsinalite | Na6(Ca,Mn2+,Fe2+)Zr(Si6O18) |
| 9.CJ.15a | Kapustinite | Na6ZrSi6O16(OH)2 |
| 9.CJ.15a | Townendite | Na8ZrSi6O18 |
| 9.CJ.15a | Combeite | Na4.5Ca3.5Si6O17.5(OH)0.5 |
| 9.CJ.15a | Kazakovite | Na6Mn2+Ti(Si6O18) |
| 9.CJ.15a | Tisinalite | Na3H3(Mn,Ca,Fe)TiSi6(O,OH)18 · 2H2O |
| 9.CJ.15a | Lovozerite | Na2Ca(Zr,Ti)(Si6O12)[(OH)4O2] · H2O |
| 9.CJ.15a | Litvinskite | Na2(◻,Na,Mn)ZrSi6O12(OH,O)6 |
| 9.CJ.15c | Koashvite | Na6(Ca,Mn)(Ti,Fe)Si6O18 · H2O |
| 9.CJ.15b | Imandrite | Na12Ca3Fe3+2(Si6O18)2 |
| 9.CJ.25 | Baratovite | KCa7(Ti,Zr)2Li3Si12O36F2 |
| 9.CJ.25 | Aleksandrovite | KCa7Sn2Li3Si12O36F2 |
| 9.CJ.25 | Katayamalite | KLi3Ca7Ti2(SiO3)12(OH)2 |
| 9.CJ.30 | Dioptase | CuSiO3 · H2O |
| 9.CJ.35 | Kostylevite | K2Zr(Si3O9) · H2O |
| 9.CJ.40 | Petarasite | Na5Zr2(Si6O18)(Cl,OH) · 2H2O |
| 9.CJ.45 | Gerenite-(Y) | (Ca,Na)2(Y,REE)3Si6O18 · 2H2O |
| 9.CJ.50 | Odintsovite | K2Na4Ca3Ti2Be4Si12O38 |
| 9.CJ.55 | Mathewrogersite | Pb7FeAl3GeSi12O36(OH,H2O)6 |
| 9.CJ.60 | Pezzottaite-(Cs) | Cs(Be2Li)Al2(Si6O18) |
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 Sekaninaite
mindat.org URL:
https://www.mindat.org/min-3609.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
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References for Sekaninaite
Reference List:
Hochella, Michael F., Brown, Gordon E., Ross, Fred K., Gibbs, G. V. (1979) High-temperature crystal chemistry of hydrous Mg- and Fe-cordierites. American Mineralogist, 64 (3-4) 337-351
Ryback, George, Nawaz, R., Farley, E. (1988) Seventh supplementary list of British Isles minerals (Irish) Mineralogical Magazine, 52 (365) 267-274
Yakubovich, O. V., Massa, V., Pekov, I. V., Gavrilenko, P. G., Chukanov, N. V. (2004) Crystal structure of the Na-, Ca-, Be-cordierite and crystallochemical regularities in the cordierite—sekaninaite series. Crystallography Reports, 49 (6) 953-963 doi:10.1134/1.1828139
Kaindl, R., Tobbens, D. M., Haefeker, U. (2011) Quantum-mechanical calculations of the Raman spectra of Mg- and Fe-cordierite. American Mineralogist, 96 (10) 1568-1574 doi:10.2138/am.2011.3845
Radica, F., Capitelli, F., Bellatreccia, F., Della Ventura, G., Cavallo, A., Piccinini, M., Hawthorne, F. C. (2013) Spectroscopy and X-ray structure refinement of sekaninaite from Dolní Bory (Czech Republic) Mineralogical Magazine, 77 (4) 485-498 doi:10.1180/minmag.2013.077.4.08
Haefeker, Udo, Kaindl, Reinhard, Tropper, Peter, Krüger, Hannes, Kahlenberg, Volker, Orlova, Maria (2014) Structural investigations of the two polymorphs of synthetic Fe-cordierite and Raman spectroscopy of hexagonal Fe-cordierite. Mineralogy and Petrology, 108 (4) 469-478 doi:10.1007/s00710-013-0313-3
Dixon, Andrea, Cempírek, Jan, Groat, Lee A. (2014) Mineralogy and geochemistry of pegmatites on Mount Begbie, British Columbia. The Canadian Mineralogist, 52 (2). 129-164 doi:10.3749/canmin.52.2.129
Novák, Milan, Čopjaková, Renata, Dosbaba, Marek, Galiová, Michaela VAŠINOVÁ, Všianský, Dalibor, Staněk, Josef (2015) Two Paragenetic Types of Cookeite From the Dolní Bory-Hatě Pegmatites, Moldanubian Zone, Czech Republic: Proximal and Distal Alteration Products of Li-Bearing Sekaninaite. The Canadian Mineralogist, 53 (6) 1035-1048 doi:10.3749/canmin.1400090
Localities for Sekaninaite
Showing 50 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 | |
| Bottrill +1 other reference |
| Birch et al. (2025) |
Austria | |
| Taucher et al. (1998) |
Brazil | |
| Fernandes et al. (2022) |
Canada | |
| Dixon et al. (2014) +1 other reference |
| D. Doell collection |
Czech Republic | |
| Škoda et al. (2004) |
| Žáček V |
| Houzar S.: Minerální asociace ... |
| Scr.Fac.Sci.Nat. Ujep Brun. (1975) +1 other reference |
| Staněk (1997) | |
| Staněk (1997) +1 other reference | |
| Staněk (1997) |
| Staněk (1997) | |
Finland | |
| Hytönen (1999) |
| Ilkka Mikkola |
Germany | |
| Keck et al. (2010) |
| Schnorrer et al. (1997) +1 other reference |
| in the collection of Christof Schäfer |
| Gottesmann et al. (2004) |
Italy | |
| Piccoli et al. (2007) |
| Grill (1935) |
| Guastoni et al. (2004) | |
| Bosi et al. (2018) |
| - (2000) +1 other reference |
| Orlandi P. & Pezzotta (1996) | |
Japan | |
| Masutomi Museum specimens +1 other reference |
| Introduction to Japanese Minerals (Geological Survey of Japan, 1970) |
| Yamada (2004) |
| American Mineralogist 87: 160-170 (2002) |
Mongolia | |
| Savina et al. (2020) +1 other reference |
Nigeria | |
| Mücke et al. (2015) |
North America Plate | |
| Reidel et al. (2023) | |
Peru | |
| Yáñez et al. (2014, May) |
Poland | |
| 86. +2 other references |
| Ł. Kruszewski EPMA/PXRD data +1 other reference |
Russia | |
| Cesnokov et al. (1998) |
| Filimonova et al. (2008) |
| Ivanyuk et al. (2007) |
| Yakovenchuk et al. (2008) | |
| Olga Yakovleva et al. (2009) | |
Slovakia | |
| Košuth (2006) |
| Ďuďa |
Sweden | |
| Damman (1989) |
Tajikistan | |
| Sharygin et al. (2009) |
UK | |
| Wilson et al. (1966) +1 other reference |
USA | |
| Reidel et al. (2023) |
| Anderson |
| Cristofono (n.d.) |
| Harvard Mineralogical Museum |
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Dolní Bory, Bory, Žďár nad Sázavou District, Vysočina Region, Czech Republic