The [9]-coordinated X site in the crystal structure of tourmaline-group minerals
-
Andreas Ertl
Abstract
The [9]-coordinated X site in tourmaline is usually occupied by Na, Ca, K, or is vacant. In contrast to earlier statements in the literature our recent evaluation of 81 tourmaline samples with Al on the Z site has clearly shown that the 〈X—O〉 distance, as could have been expected, is positively correlated to the average effective ionic radius of the X-site occupants (r = 0.98 for 81 tourmaline samples, with Al6 at the Z site and (OH)3 at the V site). Olenite and “oxy-rossmanite” samples, in which the V site is not completely occupied by OH, show a significant deviation to this correlation. X-site vacancies (up to ∼0.7 apfu), as well as a significant variation of 〈T—O〉 and 〈Y—O〉 distances, do not seem to have a significant effect on the 〈X—O〉 distance. Tourmalines of the elbaite-olenite-rossmanite series (with Al6 at the Z site) show a positive correlation between the 〈X—O〉 and the 〈Z—O〉 distance (r = 0.80; 40 samples) due to inductive effects in the structure.
© by Oldenbourg Wissenschaftsverlag, München, Germany
Articles in the same Issue
- Friedrich Liebau (1926–2011) Memorial
- On the symmetry and atomic ordering in (OH,F)-rich spessartine: towards a new hydrogarnet end-member
- Structural and 57Fe Mössbauer spectroscopic characterization of the synthetic NaFeSi2O6 (aegirine) – CaMgSi2O6 (diopside) solid solution series
- A neutron/X-Ray diffraction, IR, and 1H/29Si NMR Spectroscopic investigation of armenite: behavior of extra framework Ca cations and H2O molecules in microporous silicates
- RUB-55, a new hydrous layer silicate with silicate layers known as motives of the sodalite and octadecasil frameworks: Synthesis and crystal structure
- Crystal structure and morphology of fully hydrated zeolite Na-A
- A new borosilicate feldspar, KBSi3O8: synthesis, crystal structure and thermal behavior
- The crystal structure of aklimaite, Ca4[Si2O5(OH)2](OH)4 · 5 H2O
- The [9]-coordinated X site in the crystal structure of tourmaline-group minerals
- Crystal structure of 2M and 1A polytypes of balangeroite
- Twinnite, Pb0.8Tl0.1Sb1.3As0.8S4, the OD character and the question of its polytypism
- The new oxosilicate NaTbSi2O6: A comparison of its A- and D-type structure
- K2Ba5Si12O30 – a member of a homologous series among layered potassium barium silicates
- Synthesis and structures of two open-framework manganese phosphate-silicates
- Glass structural studies for borosilicates of the KBSi2O6—RbBSi2O6 system from X-ray diffraction data
Articles in the same Issue
- Friedrich Liebau (1926–2011) Memorial
- On the symmetry and atomic ordering in (OH,F)-rich spessartine: towards a new hydrogarnet end-member
- Structural and 57Fe Mössbauer spectroscopic characterization of the synthetic NaFeSi2O6 (aegirine) – CaMgSi2O6 (diopside) solid solution series
- A neutron/X-Ray diffraction, IR, and 1H/29Si NMR Spectroscopic investigation of armenite: behavior of extra framework Ca cations and H2O molecules in microporous silicates
- RUB-55, a new hydrous layer silicate with silicate layers known as motives of the sodalite and octadecasil frameworks: Synthesis and crystal structure
- Crystal structure and morphology of fully hydrated zeolite Na-A
- A new borosilicate feldspar, KBSi3O8: synthesis, crystal structure and thermal behavior
- The crystal structure of aklimaite, Ca4[Si2O5(OH)2](OH)4 · 5 H2O
- The [9]-coordinated X site in the crystal structure of tourmaline-group minerals
- Crystal structure of 2M and 1A polytypes of balangeroite
- Twinnite, Pb0.8Tl0.1Sb1.3As0.8S4, the OD character and the question of its polytypism
- The new oxosilicate NaTbSi2O6: A comparison of its A- and D-type structure
- K2Ba5Si12O30 – a member of a homologous series among layered potassium barium silicates
- Synthesis and structures of two open-framework manganese phosphate-silicates
- Glass structural studies for borosilicates of the KBSi2O6—RbBSi2O6 system from X-ray diffraction data
