Abstract
Bartelkeite from Tsumeb, Namibia, was originally described by Keller et al. (1981) with the chemical formula PbFeGe 3O 8. By means of electron microprobe analysis, single-crystal X-ray diffraction, and Raman spectroscopy, we examined this mineral from the type locality. Our results show that bartelkeite is monoclinic with space group P2 1/m, unit-cell parameters a = 5.8279(2), b = 13.6150(4), c = 6.3097 (2) Å, β = 127.314(2)°, and a revised ideal chemical formula PbFeGe VIGe 2 IVO 7(OH) 2·H 2O (Z = 2). Most remarkably, bartelkeite is isostructural with the high-pressure P2 1/m phase of lawsonite, CaAl 2Si 2O 7(OH)·H 2O, which is only stable above 8.6 GPa and a potential host for H 2O in subducting slabs. Its structure consists of single chains of edge-sharing FeO 6 and Ge1O 6 octahedra parallel to the c-axis, cross-linked by Ge2 2O 7 tetrahedral dimers. The average <Ge-O> bond lengths for the GeO 6 and GeO 4 polyhedra are 1.889 and 1.744 Å, respectively. The Pb atoms and H 2O groups occupy large cavities within the framework. The hydrogen bonding scheme in bartelkeite is similar to that in lawsonite. Bartelkeite represents the first known mineral containing both 4- and 6-coordinated Ge atoms and may serve as an excellent analog for further exploration of the temperature-pressure-composition space of lawsonite.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1812-1815 |
| Number of pages | 4 |
| Journal | American Mineralogist |
| Volume | 97 |
| Issue number | 10 |
| DOIs | |
| State | Published - Oct 2012 |
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Keywords
- Bartelkeite
- Crystal structure
- Germanate
- Hydrous mineral
- Raman spectra
- X-ray diffraction
ASJC Scopus subject areas
- Geochemistry and Petrology
- Geophysics
Cite this
Letter : The crystal structure of bartelkeite, with a revised chemical formula, PbFeGe VI(Ge 2 IVO 7) (OH) 2·H 2O, isotypic with high-pressure P2 1/m lawsonite. / Origlieri, Marcus J.; Yang, Hexiong; Downs, Robert T; Posner, Esther S.; Domanik, Kenneth J.; Pinch, William W.
In: American Mineralogist, Vol. 97, No. 10, 10.2012, p. 1812-1815.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Letter
T2 - The crystal structure of bartelkeite, with a revised chemical formula, PbFeGe VI(Ge 2 IVO 7) (OH) 2·H 2O, isotypic with high-pressure P2 1/m lawsonite
AU - Origlieri, Marcus J.
AU - Yang, Hexiong
AU - Downs, Robert T
AU - Posner, Esther S.
AU - Domanik, Kenneth J.
AU - Pinch, William W.
PY - 2012/10
Y1 - 2012/10
N2 - Bartelkeite from Tsumeb, Namibia, was originally described by Keller et al. (1981) with the chemical formula PbFeGe 3O 8. By means of electron microprobe analysis, single-crystal X-ray diffraction, and Raman spectroscopy, we examined this mineral from the type locality. Our results show that bartelkeite is monoclinic with space group P2 1/m, unit-cell parameters a = 5.8279(2), b = 13.6150(4), c = 6.3097 (2) Å, β = 127.314(2)°, and a revised ideal chemical formula PbFeGe VIGe 2 IVO 7(OH) 2·H 2O (Z = 2). Most remarkably, bartelkeite is isostructural with the high-pressure P2 1/m phase of lawsonite, CaAl 2Si 2O 7(OH)·H 2O, which is only stable above 8.6 GPa and a potential host for H 2O in subducting slabs. Its structure consists of single chains of edge-sharing FeO 6 and Ge1O 6 octahedra parallel to the c-axis, cross-linked by Ge2 2O 7 tetrahedral dimers. The average <Ge-O> bond lengths for the GeO 6 and GeO 4 polyhedra are 1.889 and 1.744 Å, respectively. The Pb atoms and H 2O groups occupy large cavities within the framework. The hydrogen bonding scheme in bartelkeite is similar to that in lawsonite. Bartelkeite represents the first known mineral containing both 4- and 6-coordinated Ge atoms and may serve as an excellent analog for further exploration of the temperature-pressure-composition space of lawsonite.
AB - Bartelkeite from Tsumeb, Namibia, was originally described by Keller et al. (1981) with the chemical formula PbFeGe 3O 8. By means of electron microprobe analysis, single-crystal X-ray diffraction, and Raman spectroscopy, we examined this mineral from the type locality. Our results show that bartelkeite is monoclinic with space group P2 1/m, unit-cell parameters a = 5.8279(2), b = 13.6150(4), c = 6.3097 (2) Å, β = 127.314(2)°, and a revised ideal chemical formula PbFeGe VIGe 2 IVO 7(OH) 2·H 2O (Z = 2). Most remarkably, bartelkeite is isostructural with the high-pressure P2 1/m phase of lawsonite, CaAl 2Si 2O 7(OH)·H 2O, which is only stable above 8.6 GPa and a potential host for H 2O in subducting slabs. Its structure consists of single chains of edge-sharing FeO 6 and Ge1O 6 octahedra parallel to the c-axis, cross-linked by Ge2 2O 7 tetrahedral dimers. The average <Ge-O> bond lengths for the GeO 6 and GeO 4 polyhedra are 1.889 and 1.744 Å, respectively. The Pb atoms and H 2O groups occupy large cavities within the framework. The hydrogen bonding scheme in bartelkeite is similar to that in lawsonite. Bartelkeite represents the first known mineral containing both 4- and 6-coordinated Ge atoms and may serve as an excellent analog for further exploration of the temperature-pressure-composition space of lawsonite.
KW - Bartelkeite
KW - Crystal structure
KW - Germanate
KW - Hydrous mineral
KW - Raman spectra
KW - X-ray diffraction
UR - http://www.scopus.com/inward/record.url?scp=84867340547&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84867340547&partnerID=8YFLogxK
U2 - 10.2138/am.2012.4269
DO - 10.2138/am.2012.4269
M3 - Article
AN - SCOPUS:84867340547
VL - 97
SP - 1812
EP - 1815
JO - American Mineralogist
JF - American Mineralogist
SN - 0003-004X
IS - 10
ER -