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Lehmannite
A valid IMA mineral species
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About Lehmannite
Johann G. Lehmann
Formula:
Na18Cu12TiO8(AsO4)8FCl5
Colour:
Dark greyish green to olive-greenish black
Lustre:
Vitreous
Hardness:
4½
Specific Gravity:
3.676 (Calculated)
Crystal System:
Monoclinic
Name:
Name in honour of Johann Gottlob Lehmann (4 August 1719, Langenhennersdorf, Electorate of Saxony – 22 January 1767, Saint Petersburg, Russian Empire) the outstanding German and Russian mineralogist and geologist, and one of the founders of stratigraphy.
Closely related to arsmirandite with which it was co-described.
The two have similar, unique structural features:
- Ti4+ (or Fe3+, in arsmirandite) in cubic coordination;
- packing of unusual, nanoscale (~1.5 nm across) clusters, of the {[MCu12O8](AsO4)8} composition; M = Ti4+ in lehmannite
Na and halogen atoms are between the nanoclusters.
See also Lehmannite (of Brooke).
Associates also include various arseantes and sulfates.
The two have similar, unique structural features:
- Ti4+ (or Fe3+, in arsmirandite) in cubic coordination;
- packing of unusual, nanoscale (~1.5 nm across) clusters, of the {[MCu12O8](AsO4)8} composition; M = Ti4+ in lehmannite
Na and halogen atoms are between the nanoclusters.
See also Lehmannite (of Brooke).
Associates also include various arseantes and sulfates.
Unique Identifiers
Mindat ID:
53217
Long-form identifier:
mindat:1:1:53217:0
Similar Names
| Lehmannite (of Brooke) | A synonym of Crocoite | |
| Lemoynite | A valid IMA mineral species | (Na,K)2CaZr2Si10O26 · 5H2O |
IMA Classification of Lehmannite
Approved
IMA Formula:
Na18Cu2+12Ti4+O8(As5+O4)8FCl5
Approval year:
2018
First published:
2020
Classification of Lehmannite
8.BK.35
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
K : With medium-sized and large cations, (OH, etc.):RO4 = 2:1, 2.5:1
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
K : With medium-sized and large cations, (OH, etc.):RO4 = 2:1, 2.5:1
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 |
|---|---|---|
| Leh | 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 Lehmannite
Vitreous
Transparency:
Translucent, Opaque
Comment:
"Strong vitreous"
Colour:
Dark greyish green to olive-greenish black
Comment:
Translucent only in thin sections.
Streak:
Greyish green with an olive hue.
Hardness:
4½ on Mohs scale
Hardness:
VHN100=339 - 537 kg/mm2 - Vickers
Comment:
Mohs estimated from VHN.
Tenacity:
Brittle
Cleavage:
None Observed
Parting:
None observed.
Fracture:
Irregular/Uneven
Density:
3.676 g/cm3 (Calculated)
Optical Data of Lehmannite
Anisotropism:
Very weak.
Bireflectance:
Very weak.
Reflectivity:
| Wavelength | R1 (%) | R2 (%) |
|---|---|---|
| 400nm | 8.3% | 8.9% |
| 420nm | 8.2% | 8.9% |
| 440nm | 8.2% | 8.8% |
| 460nm | 8.1% | 8.7% |
| 470nm | 8.1% | 8.7% |
| 480nm | 8.1% | 8.7% |
| 500nm | 8.0% | 8.7% |
| 520nm | 8.0% | 8.6% |
| 540nm | 7.9% | 8.6% |
| 546nm | 7.9% | 8.5% |
| 560nm | 7.9% | 8.5% |
| 580nm | 7.8% | 8.5% |
| 589nm | 7.6% | 8.4% |
| 600nm | 7.7% | 8.4% |
| 620nm | 7.7% | 8.4% |
| 640nm | 7.6% | 8.3% |
| 650nm | 7.6% | 8.3% |
| 660nm | 7.6% | 8.3% |
| 680nm | 7.5% | 8.2% |
| 700nm | 7.5% | 8.1% |
Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 8.9%.
R1 shown in black, R2 shown in red
Colour in reflected light:
Dark grey.
Internal Reflections:
Weak, brown.
Pleochroism:
Not Visible
Chemistry of Lehmannite
Mindat Formula:
Na18Cu12TiO8(AsO4)8FCl5
Element Weights:
Crystallography of Lehmannite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Setting:
C2/m
Cell Parameters:
a = 10.824(1) Å, b = 21.108(2) Å, c = 11.856(1) Å
β = 117.195(8)°
β = 117.195(8)°
Ratio:
a:b:c = 0.513 : 1 : 0.562
Unit Cell V:
2409.2 ų
Morphology:
Individual crystals are equant, thick tabular or short prismatic, with pyramid-like terminations.
Twinning:
Cyclic interpenetration twins, similar to phillipsite.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 10.52 Å | (65) |
| 8.74 Å | (100) |
| 5.419 Å | (36) |
| 5.273 Å | (74) |
| 3.722 Å | (37) |
| 2.636 Å | (43) |
| 2.573 Å | (98) |
| 1.889 Å | (33) |
Comments:
Arsenatnaya fumarole, Kamchatka Krai, Russia. Data from the type description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 45a : [Sulfates, arsenates, selenates, antimonates] | |
| 45b : [Other oxidized fumarolic minerals] |
Geological Setting:
Volcanic fumarole
Type Occurrence of Lehmannite
General Appearance of Type Material:
Equant crystals, up to 20 × 20 × 30 sq. μm, usually intergrown to form thin crusts, up to 2 × 3 cm in area.
Place of Conservation of Type Material:
Type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Leninskiy Prospekt 18-2, Moscow 119071, Russia, registration number 5065/1.
Geological Setting of Type Material:
Volcanic fumarole.
Associated Minerals at Type Locality:
Synonyms of Lehmannite
Other Language Names for Lehmannite
Dutch:Lehmanniet
German:Lehmannit
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 8.BK.05 | Brazilianite | NaAl3(PO4)2(OH)4 |
| 8.BK.10 | Neustädtelite | Bi2Fe3+(Fe3+,Co)(AsO4)2(O,OH)4 |
| 8.BK.10 | Cobaltneustädtelite | Bi2Fe3+(Co,Fe3+)(AsO4)2(O,OH)4 |
| 8.BK.10 | Medenbachite | Bi2Fe3+Cu2+(AsO4)2O(OH)3 |
| 8.BK.15 | Curetonite | Ba(Al,Ti)(PO4)(OH,O)F |
| 8.BK.20 | Heyite | Pb5Fe2+2(VO4)2O4 |
| 8.BK.25 | Jamesite | Pb2Zn(Fe2+,Zn)2Fe3+4(AsO4)4(OH)10 |
| 8.BK.25 | Lulzacite | Sr2Fe2+(Fe2+,Mg)2Al4(PO4)4(OH)10 |
| 8.BK.25 | Désorite | Pb2(Fe3+6Zn)O2(PO4)4(OH)8 |
| 8.BK.30 | Nishanbaevite | KAl2O(AsO4)(SO4) |
| 8.BK.35 | Zircarsite | Na18Cu12ZrO8(AsO4)8Cl6 |
| 8.BK.35 | Arsmirandite | Na18Cu12Fe3+O8(AsO4)8Cl5 |
| 8.BK.35 | Lebedevite | K4Na14Cu14O8(AsO4)8Cl6 |
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 Lehmannite
mindat.org URL:
https://www.mindat.org/min-53217.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
Arsenatnaya fumarole, Second scoria cone, Northern Breakthrough, Great Fissure eruption, Tolbachik Volcanic field, Milkovsky District, Kamchatka Krai, Russia