Bartelkeite
A valid IMA mineral species
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About Bartelkeite
Formula:
Pb(Fe2+Ge)[Ge2O7](OH)2 · H2O
Colour:
Colourless or white to olive or yellowish-green.
Lustre:
Sub-Adamantine
Hardness:
4
Specific Gravity:
4.97 (Calculated)
Crystal System:
Monoclinic
Name:
Name in honor of Wolfgang Bartelke (b. 1949), German mineral collector and specialist in the minerals of Tsumeb, Namibia.
Structurally related to the monoclinic non-quenchable high-pressure phase of lawsonite (lawsonite itself is orthorhombic).
Chemically related to mathewrogersite.
Chemically related to mathewrogersite.
Unique Identifiers
Mindat ID:
541
Long-form identifier:
mindat:1:1:541:8
IMA Classification of Bartelkeite
Classification of Bartelkeite
9.J0.10
9 : SILICATES (Germanates)
J : Germanates
0 :
9 : SILICATES (Germanates)
J : Germanates
0 :
7.6.2.1
7 : MULTIPLE OXIDES
6 : (AB)5X8
7 : MULTIPLE OXIDES
6 : (AB)5X8
7.11.19
7 : Oxides and Hydroxides
11 : Oxides of Sn and Pb
7 : Oxides and Hydroxides
11 : Oxides of Sn and Pb
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 |
|---|---|---|
| Btk | 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 Bartelkeite
Sub-Adamantine
Transparency:
Transparent
Colour:
Colourless or white to olive or yellowish-green.
Streak:
White
Hardness:
4 on Mohs scale
Cleavage:
Distinct/Good
on {101}
on {101}
Density:
4.97 g/cm3 (Calculated)
Optical Data of Bartelkeite
Type:
Biaxial (-)
RI values:
nα = 1.885 nβ = 1.91 nγ = 1.913
2V:
Measured: 35°
Max. Birefringence:
δ = 0.028
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
Chemistry of Bartelkeite
Mindat Formula:
Pb(Fe2+Ge)[Ge2O7](OH)2 · H2O
Element Weights:
Crystallography of Bartelkeite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/m
Setting:
P121/m1
Cell Parameters:
a = 5.8279(2) Å, b = 13.6150(4) Å, c = 6.3097(2) Å
β = 127.314(2)°
β = 127.314(2)°
Ratio:
a:b:c = 0.428 : 1 : 0.463
Unit Cell V:
398.18 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Crystals tabular on {101} or acicular on {101}; {111} and {010} also observed.
Comment:
contains Ge in both octahedral coordination with Fe, and in tetrahedral coordination as sorogermanate anion [Ge2O7]
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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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) |
|---|---|---|---|---|---|---|---|
| 0019471 | Bartelkeite | Origlieri M J, Yang H, Downs R T, Posner E S, Domanik K J, Pinch W W (2012) The crystal structure of bartelkeite, with a revised chemical formula, PbFeGeVI(GeIV2O7)(OH)2*H2O, isotypic with high-pressure P21/m lawsonite American Mineralogist 97 1812-1815 | 2012 | Tsumeb, Namibia | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.91 Å | (10) |
| 4.42 Å | (8) |
| 2.87 Å | (8) |
| 2.75 Å | (7) |
| 2.20 Å | (7) |
| 4.74 Å | (6) |
| 5.08 Å | (5) |
Comments:
Recorded on type material.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] |
Type Occurrence of Bartelkeite
General Appearance of Type Material:
Tabular and acicular crystals to 1 mm.
Place of Conservation of Type Material:
University of Stuttgart, Stuttgart, Germany (No. NM07);
National Museum of Natural History, Washington, D.C., USA (No. 148302).
National Museum of Natural History, Washington, D.C., USA (No. 148302).
Geological Setting of Type Material:
In cavities in oxidized primary germanium ore from a dolostone-hosted hydrothermal polymetallic ore deposit.
Associated Minerals at Type Locality:
Synonyms of Bartelkeite
Other Language Names for Bartelkeite
Common Associates
Associations Based on Photo Data:
| 3 photos of Bartelkeite associated with Chalcocite | Cu2S |
| 2 photos of Bartelkeite associated with Siderite | FeCO3 |
| 1 photo of Bartelkeite associated with Galloplumbogummite | Pb(Ga,Al,Ge)3(PO4)2(OH)6 |
| 1 photo of Bartelkeite associated with Plumbogummite | PbAl3(PO4)(PO3OH)(OH)6 |
Related Minerals - Strunz-mindat Grouping
| 9.J0.05 | Carboirite | Fe2+Al2O(GeO4)(OH)2 |
| 9.J0.15 | Otjisumeite | PbGe4O9 |
Other Information
IR Spectrum:
IR spectrum shows the absence of water.
Notes:
Dissolves in hot HCl.
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 Bartelkeite
mindat.org URL:
https://www.mindat.org/min-541.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Bartelkeite
Reference List:
Origlieri, M. J., Yang, H., Downs, R. T., Posner, E. S., Domanik, K. J., Pinch, W. W. (2012) The crystal structure of bartelkeite, with a revised chemical formula, PbFeGeVI(Ge2IVO7)(OH)2·H2O, isotypic with high-pressure P21/m lawsonite. American Mineralogist, 97 (10) 1812-1815 doi:10.2138/am.2012.4269
Localities for Bartelkeite
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.
Namibia (TL) | |
| Keller et al. (1981) |
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Tsumeb Mine, Tsumeb, Oshikoto Region, Namibia