Characterization, axial anisotropy and formation conditions of celestine from Jabal Eghei (Libya)

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Marco E. Ciriotti
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Characterization, axial anisotropy and formation conditions of celestine from Jabal Eghei (Libya)

Messaggio da Marco E. Ciriotti » sab 04 feb, 2023 10:23

Prossima pubblicazione.

Referenza:
▪ Tančić, P., Milošević, M., Spahić, D., Kostić, B., Kremenović, A., Poznanović-Spahić, M., Kovačević, J. (2024): Characterization, axial anisotropy and formation conditions of celestine minerals from the Jabal Eghei (Nuqay) volcanic province (southeastern edge of the Sirt Basin, southern Libya). Mineralogical Magazine, 88, (in press).

Abstract:
Five celestine crystals, sampled from the surface at the Miocene to Pliocene Jabal Eghei (Nuqay) volcanic province (southern Libya), are characterized by applying the combination of the SEM-WDS, XRPD and IR methods; and analyzed for their color variations and minerogenesis. Three samples have greenish-blue to blue (480.4−482.5 nm), whereas the other two samples are of blue-green color (cyan; 489.1−494.1 nm). The color purity is in the 1.36–7.16 range. Their chemical composition is mutually similar, fitting into the celestine near-end members, in which exclusively 1.6–4.1 at. % of Sr2 + contents was substituted by Pb2+ (0.7–0.9 at. %), Ba2+ (0.5–0.7 at. %) and Ca2+ (0.2–0.8 at. %); including the vacancies (1.0−1.9 at. %; only in three samples). The resulting unit-cell parameters have the following ranges: a0 = 8.3578(9)−8.3705(6) Å; b0 = 5.3510(5)−5.3568(4) Å; c0 = 6.8683(7)−6.8767(2) Å and V0 = 307.17(5)−308.34(4) Å3. The XRPD and IR results are mainly in accordance with the SEM-WDS analyses, having higher mutual correlativity. However, a few discrepancies among the results are observed, further yielding several possible interpretations. The overall results show that discrepancies were primarily induced by a slight unit-cell axial anisotropy, occurring as a consequence of their thermal expansion. Essentially, the investigated Sr-bearing celestines were formed as a secondary volcanic system, emplaced over the gypsum and/or anhydrite minerals, at ~ 368−430K (~ 95–157 oC) temperature range, in the ambient pressure conditions. The study further shows that the investigated celestine minerals are likely formed at a slightly elevated temperature and pressure subsurface environment, reaching over 250 bars.
Marco E. Ciriotti

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Marco E. Ciriotti
Messaggi: 31675
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
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Re: Characterization, axial anisotropy and formation conditions of celestine from Jabal Eghei (Libya)

Messaggio da Marco E. Ciriotti » mer 28 feb, 2024 9:42

Referenza:
▪ Tančić, P., Milošević, M., Spahić, D., Kostić, B., Kremenović, A., Poznanović-Spahić, M., Kovačević, J. (2023): Characterization, axial anisotropy and formation conditions of celestine minerals from the Jabal Eghei (Nuqay) volcanic province (southeastern edge of the Sirt Basin, southern Libya) - ERRATUM. Mineralogical Magazine, 88, (in press).
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

Avatar utente
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:

Re: Characterization, axial anisotropy and formation conditions of celestine from Jabal Eghei (Libya)

Messaggio da Marco E. Ciriotti » ven 08 mar, 2024 10:21

Pubblicazione effettuata.

Referenza:
▪ Tančić, P., Milošević, M., Spahić, D., Kostić, B., Kremenović, A., Poznanović-Spahić, M., Kovačević, J. (2024): Characterization, axial anisotropy and formation conditions of celestine minerals from the Jabal Eghei (Nuqay) volcanic province (southeastern edge of the Sirt Basin, southern Libya). Mineralogical Magazine, 88, 1-18.
Marco E. Ciriotti

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