Jørgensenite
A valid IMA mineral species
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About Jørgensenite
Vilhelm C. Jørgensen
Formula:
Na2(Sr,Ba)14Na2Al12F64(OH,F)4
Colour:
Colourless
Lustre:
Vitreous
Hardness:
3½ - 4
Specific Gravity:
3.89
Crystal System:
Monoclinic
Name:
Named in honor of Vilhelm Carl Jørgensen (2 May 1844, Tiselholt, Vejstrup Sogn, Denmark - 13 September 1925, Løndal near Silkeborg, Denmark), cofounder (with G.A. Hagemann) of the cryolite factory at Ivigtut in 1870.
Name Encoding
ASCII-7:
Jorgensenite
Unique Identifiers
Mindat ID:
7121
Long-form identifier:
mindat:1:1:7121:1
IMA Classification of Jørgensenite
Approved
IMA Formula:
Na2Sr14Na2Al12F64(OH)4
Approval year:
1995
First published:
1997
Classification of Jørgensenite
3.CC.20
3 : HALIDES
C : Complex halides
C : Soro-aluminofluorides
3 : HALIDES
C : Complex halides
C : Soro-aluminofluorides
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 |
|---|---|---|
| Jør | 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 Jørgensenite
Vitreous
Transparency:
Transparent
Colour:
Colourless
Streak:
White
Hardness:
3½ - 4 on Mohs scale
Tenacity:
Brittle
Fracture:
Irregular/Uneven
Density:
3.89(1) g/cm3 (Measured) 3.94 g/cm3 (Calculated)
Optical Data of Jørgensenite
Type:
Biaxial (-)
RI values:
nα = 1.436 nβ = 1.442 nγ = 1.442
Max. Birefringence:
δ = 0.006
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:
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
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.
No measured or calculated 2V is on file for this mineral, so the value used here (-0°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
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.
No measured or calculated 2V is on file for this mineral, so the value used here (-0°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Dispersion:
dispersion not observed
Pleochroism:
Non-pleochroic
Chemistry of Jørgensenite
Mindat Formula:
Na2(Sr,Ba)14Na2Al12F64(OH,F)4
Element Weights:
Crystallography of Jørgensenite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 16.059(7) Å, b = 10.974(4) Å, c = 7.277(3) Å
β = 101.70(3)°
β = 101.70(3)°
Ratio:
a:b:c = 1.463 : 1 : 0.663
Unit Cell V:
1,255.79 ų (Calculated from Unit Cell)
Z:
1
Morphology:
Prisms elongated along [010].
Twinning:
None observed
Comment:
SG C2/m.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.844 Å | (8) |
| 3.643 Å | (9) |
| 3.453 Å | (10) |
| 3.193 Å | (10) |
| 3.112 Å | (9) |
| 2.989 Å | (9) |
| 2.173 Å | (9) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 23 : Subaerial aqueous alteration by non-redox-sensitive fluids (see also #47) |
Type Occurrence of Jørgensenite
General Appearance of Type Material:
Fissure fillings within the main cryolite mass, and in crystal-lined cavities containing fan-shaped aggregates (up to 2 mm across) of jorgensenite overgrown by jarlite.
Place of Conservation of Type Material:
The Geological Museum, University of Copenhagen,Copenhagen, fluorDenmark, catalogue number 1996.168.
Synonyms of Jørgensenite
Other Language Names for Jørgensenite
Common Associates
Associations Based on Photo Data:
| 6 photos of Jørgensenite associated with Weberite | Na2Mg[AlF6]F |
| 5 photos of Jørgensenite associated with Baryte | BaSO4 |
| 3 photos of Jørgensenite associated with Thomsenolite | NaCa[AlF6] · H2O |
| 3 photos of Jørgensenite associated with Fluorite | CaF2 |
| 2 photos of Jørgensenite associated with 'Sericite' | KAl2(AlSi3O10)(OH)2 |
| 2 photos of Jørgensenite associated with Muscovite | KAl2(AlSi3O10)(OH)2 |
| 1 photo of Jørgensenite associated with Topaz | Al2(SiO4)(F,OH)2 |
Related Minerals - Strunz-mindat Grouping
| 3.CC.05 | Gearksutite | Ca[Al(F,OH)5(H2O)] |
| 3.CC.10 | Acuminite | Sr[AlF4(OH)(H2O)] |
| 3.CC.10 | Tikhonenkovite | Sr[AlF4(OH)(H2O)] |
| 3.CC.15 | Artroeite | Pb[AlF3(OH)2] |
| 3.CC.20 | Jarlite | Na(Sr,Na)7MgAl6F32(OH,H2O)2 |
| 3.CC.20 | Calcjarlite | Na(Ca,Sr)3Al3(OH)2F14 |
Fluorescence of Jørgensenite
None
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 Jørgensenite
mindat.org URL:
https://www.mindat.org/min-7121.html
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Please feel free to link to this page.
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References for Jørgensenite
Reference List:
Localities for Jørgensenite
Showing 1 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.
Greenland (TL) | |
| Can. Mineral. |
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Ivigtut Mine, Ivigtut stock, Arsuk Fjord, Sermersooq, Greenland