Lüneburgite
A valid IMA mineral species - grandfathered
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About Lüneburgite
Town hall of Lüneburg, Germany
Formula:
Mg3[B2(OH)6](PO4)2 · 6H2O
Colour:
White to brownish or green, colorless
Lustre:
Vitreous
Hardness:
2
Specific Gravity:
2.05
Crystal System:
Triclinic
Name:
After the type locality, Lüneburg, Germany.
Lüneburgite is found in clays with evaporite minerals (halite, sylvite, polyhalite, etc.) and has also been found in guano deposits.
Name Encoding
ASCII-7:
Luneburgite
Unique Identifiers
Mindat ID:
2458
Long-form identifier:
mindat:1:1:2458:3
IMA Classification of Lüneburgite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Mg3[B2(OH)6(PO4)2](H2O)6
First published:
1870
Classification of Lüneburgite
6.AC.60
6 : BORATES
A : Monoborates
C : B(O,OH)4, without and with additional anions; 1(T), 1(T)+OH, etc
6 : BORATES
A : Monoborates
C : B(O,OH)4, without and with additional anions; 1(T), 1(T)+OH, etc
43.5.11.1
43 : COMPOUND PHOSPHATES, ETC.
5 : Hydrated Compound Phosphates, etc·, Containing Hydroxyl or Halogen
43 : COMPOUND PHOSPHATES, ETC.
5 : Hydrated Compound Phosphates, etc·, Containing Hydroxyl or Halogen
10.2.1
10 : Borates with other anions
2 : Borates with phosphate or arsenate
10 : Borates with other anions
2 : Borates with phosphate or arsenate
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 |
|---|---|---|
| Lbu | 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 Lüneburgite
Vitreous
Transparency:
Translucent
Colour:
White to brownish or green, colorless
Hardness:
2 on Mohs scale
Cleavage:
Poor/Indistinct
Prismatic cleavage with an angle of about 73° (viewed microscopically). Minute pseudo-hexagonal plates.
On {010}, fair.
Prismatic cleavage with an angle of about 73° (viewed microscopically). Minute pseudo-hexagonal plates.
On {010}, fair.
Density:
2.05 g/cm3 (Measured) 2.204 g/cm3 (Calculated)
Optical Data of Lüneburgite
Type:
Biaxial (-)
RI values:
nα = 1.520 - 1.522 nβ = 1.54 - 1.541 nγ = 1.545 - 1.549
2V:
Measured: 63° , Calculated: 62° to 60°
Max. Birefringence:
δ = 0.025 - 0.027
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:
None to Very Low
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:
distinct to strong
Chemistry of Lüneburgite
Mindat Formula:
Mg3[B2(OH)6](PO4)2 · 6H2O
Element Weights:
Crystallography of Lüneburgite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 6.3475(6) Å, b = 9.8027(11) Å, c = 6.2976(5) Å
α = 84.456(9)°, β = 106.402(8)°, γ = 96.400(9)°
α = 84.456(9)°, β = 106.402(8)°, γ = 96.400(9)°
Ratio:
a:b:c = 0.648 : 1 : 0.642
Unit Cell V:
372.69 ų (Calculated from Unit Cell)
Z:
1
Morphology:
Flattened masses and nodules with fine fibrous to earthy structure. Minute pseudo-hexagonal tablets.
Twinning:
Common, by rotation about [110].
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 4.98 Å | (100) |
| 4.85 Å | (70) |
| 2.964 Å | (60) |
| 2.819 Å | (45) |
| 3.23 Å | (40) |
| 2.507 Å | (35) |
| 3.027 Å | (30) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 25 : Evaporites (prebiotic) |
Type Occurrence of Lüneburgite
Place of Conservation of Type Material:
Wroclaw University, Wroclaw, Poland, 1I-5734; National Museum of Natural History, Washington, D.C., USA, 162602.
Geological Setting of Type Material:
Gypsum-bearing marl.
Associated Minerals at Type Locality:
Synonyms of Lüneburgite
Other Language Names for Lüneburgite
Dutch:Lüneburgiet
Russian:Люнебургит
Simplified Chinese:硼磷镁石
Spanish:Lueneburgita
Luneburgita
Luneburgita
Traditional Chinese:硼磷鎂石
Related Minerals - Strunz-mindat Grouping
| 6.AC.05 | Sinhalite | MgAl(BO4) |
| 6.AC.10 | Pseudosinhalite | Mg2Al3(BO3)2(OH)O3 |
| 6.AC.15 | Béhierite | Ta(BO4) |
| 6.AC.15 | Schiavinatoite | Nb(BO4) |
| 6.AC.20 | Frolovite | Ca[B(OH)4]2 |
| 6.AC.25 | Hexahydroborite | Ca[B(OH)4]2 · 2H2O or CaB2O4 · 6H2O |
| 6.AC.30 | Henmilite | Ca2Cu[B(OH)4]2(OH)4 |
| 6.AC.35 | Bandylite | Cu[B(OH)4]Cl |
| 6.AC.40 | Teepleite | Na2[B(OH)4]Cl |
| 6.AC.45 | Moydite-(Y) | Y[B(OH)4](CO3) |
| 6.AC.50 | Carboborite | Ca2Mg[B(OH)4]2(CO3)2 · 4H2O |
| 6.AC.55 | Sulfoborite | Mg3[B(OH)4]2(SO4)(OH,F)2 |
| 6.AC.65 | Seamanite | Mn2+3[B(OH)4](PO4)(OH)2 |
| 6.AC.70 | Cahnite | Ca2[B(OH)4](AsO4) |
Other Information
IR Spectrum:
Bulganak volcano material [cm-1]: 3495, 3440, 3390s, 3250sh, 3215, 3100, 2965, 2625w, 1665, 1325sh, 1283, 1185, 1122s, 1075s, 973, 891s, 830sh, 783, 712, 664, 638, 576, 537, 520sh, 462w
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 Lüneburgite
mindat.org URL:
https://www.mindat.org/min-2458.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 Lüneburgite
Reference List:
Larsen, Esper S. (1921) The microscopic determination of the nonopaque minerals. Bulletin 679. US Geological Survey doi:10.3133/b679 p.103
Braitsch, Otto (1961) Neue Daten für Lüneburgit und Sulfoborit. Beiträge zur Mineralogie und Petrographie, 8 (1). 60-66 doi:10.1007/bf01104960
Gupta, P. K. Sen, Swihart, George H., Dimitrijevic, R., Hossain, M. B. (1991) The crystal structure of lüneburgite, Mg3(H2O)6[B2(OH)6(PO4)2]. American Mineralogist, 76 (7-8) 1400-1407
Localities for Lüneburgite
Showing 17 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.
Chile | |
| Gupta et al. (1991) |
| SEM-EDS by Igor V. Pekov | |
China | |
| Dongyan Wei (1985) | |
Germany | |
| Braitsch (1961) |
| C. Noellner: "Über Lüneburgit" (1876) +1 other reference |
| Nöllner (1870) |
| Heide et al. (1964) |
Serbia | |
| Obradovic et al. (1992) |
Turkey | |
| Helvaci et al. (2004) |
| Ortı́ et al. (2002) |
Turkmenistan | |
| Evseev (1995) |
| Mineralogical Society of America - ... | |
Ukraine | |
| Shnykov E.F. at al. (1971) |
USA | |
| Field collected by Gunnar Färber |
| Palache et al. (1951) |
| Palache et al. (1951) | |
| Mineralogical Society of America - ... |
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Volgershall, Lüneburg, Lüneburg District, Lower Saxony, Germany