Segnalo un interessante lavoro, appena uscito sull'European Journal of Mineralogy di dicembre 2004, su minerali di zirconio e titanio di Pian di Celle, San Venanzo, Terni, Umbria.
• Bellezza, M., Merlino, S., Perchiazzi, N. (2004): Chemical and structural study of the Zr, Ti-disilicates in the venanzite from Pian di Celle, Umbria, Italy. European Journal of Mineralogy, 16, 957-970.
Abstract a seguire.
Zr- e Ti-disilicati di Pian di Celle, Umbria: studio UniPisa
- Marco E. Ciriotti
- Messaggi: 31675
- Iscritto il: ven 25 giu, 2004 11:31
- Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
- Contatta:
Zr- e Ti-disilicati di Pian di Celle, Umbria: studio UniPisa
Marco E. Ciriotti
«Things are interesting only in so far as they relate themselves to other things»
«Things are interesting only in so far as they relate themselves to other things»
- Marco E. Ciriotti
- Messaggi: 31675
- Iscritto il: ven 25 giu, 2004 11:31
- Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
- Contatta:
Riportiamo ora referenza e abstract dell'articolo citato nel messaggio precedente, concernente studi su cuspidina e götzenite di Pian di Celle, San Venanzo, Terni, Umbria, Italia.
• Bellezza, M., Merlino, S., Perchiazzi, N. (2004): Chemical and structural study of the Zr, Ti-disilicates in the venanzite from Pian di Celle, Umbria, Italy. European Journal of Mineralogy, 16, 957-970.
Abstract: Cuspidine and götzenite were found as accessories in the pegmatitoid facies of venanzite from the Pleistocene lava flow of Pian di Celle. The modal compositions of venanzite and its pegmatitoid facies have been defined through combined XRF and Rietveld quantitative analyses. Cuspidine and götzenite were unambiguously identified by combining microprobe analyses and structural studies.
The structure analyses were carried on with single-crystal XRD data and the refinements converged to R1 = 0.048 and 0.053 for cuspidine and götzenite respectively.
Cuspidine from Pian di Celle, ideally (Ca,Zr)Ca2(Ca,Na)Si2O7F2, Z = 4, space group P21/a, a = 10.919(2), b = 10.485(1), c = 7.485(1) Å, β = 109.55(1)°, represents a Zr, Na-rich variety of cuspidine.
Götzenite from Pian di Celle, ideally (Ca,Zr) (Ca,Na)Ca(Na,Ca)0.5Ti0.5Si2O7(F,OH,O)2, Z = 2, space group P1, a = 9.636(3), b = 7.341(2), c = 5.737(1) Å, α = 89.94(2), β = 100.74(2), γ = 101.06(3)°, represents a Zr-rich variety of götzenite.
Zirconium and sodium enter in the structures substituting part of calcium, according to the main substitution indicated by the chemical data: 2Ca2+ + F ↔ Na+ + (Zr+Ti)4+ + O2-.
• Bellezza, M., Merlino, S., Perchiazzi, N. (2004): Chemical and structural study of the Zr, Ti-disilicates in the venanzite from Pian di Celle, Umbria, Italy. European Journal of Mineralogy, 16, 957-970.
Abstract: Cuspidine and götzenite were found as accessories in the pegmatitoid facies of venanzite from the Pleistocene lava flow of Pian di Celle. The modal compositions of venanzite and its pegmatitoid facies have been defined through combined XRF and Rietveld quantitative analyses. Cuspidine and götzenite were unambiguously identified by combining microprobe analyses and structural studies.
The structure analyses were carried on with single-crystal XRD data and the refinements converged to R1 = 0.048 and 0.053 for cuspidine and götzenite respectively.
Cuspidine from Pian di Celle, ideally (Ca,Zr)Ca2(Ca,Na)Si2O7F2, Z = 4, space group P21/a, a = 10.919(2), b = 10.485(1), c = 7.485(1) Å, β = 109.55(1)°, represents a Zr, Na-rich variety of cuspidine.
Götzenite from Pian di Celle, ideally (Ca,Zr) (Ca,Na)Ca(Na,Ca)0.5Ti0.5Si2O7(F,OH,O)2, Z = 2, space group P1, a = 9.636(3), b = 7.341(2), c = 5.737(1) Å, α = 89.94(2), β = 100.74(2), γ = 101.06(3)°, represents a Zr-rich variety of götzenite.
Zirconium and sodium enter in the structures substituting part of calcium, according to the main substitution indicated by the chemical data: 2Ca2+ + F ↔ Na+ + (Zr+Ti)4+ + O2-.
Marco E. Ciriotti
«Things are interesting only in so far as they relate themselves to other things»
«Things are interesting only in so far as they relate themselves to other things»
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