Prossima pubblicazione.
Referenza:
▪ Garavelli, A., Pinto, D., Mitolo, D., Kolitsch, U. (2021): Thermessaite-(NH4), (NH4)2AlF3(SO4), a new fumarole mineral from La Fossa crater at Vulcano, Aeolian Islands, Italy. Mineralogical Magazine, 85, (in press).
Abstract:
Thermessaite-(NH4), ideally (NH4)2AlF3(SO4), is a new mineral found as a medium- to high-temperature (about 250-300°C) fumarole encrustation at the rim of La Fossa crater, Vulcano, Aeolian Islands, Italy. The mineral deposited as aggregates of micrometer-sized sharp prismatic crystals on the surface of a pyroclastic breccia in association with thermessaite, sulfur, arcanite, mascagnite, and intermediate members of the arcanite-mascagnite series.
The new mineral is colorless to white, transparent, non-fluorescent, has a vitreous luster, and a white streak. The calculated density is 2.185 g/cm3. Thermessaite-(NH4) is orthorhombic, space group Pbcn, with a = 11.3005(3) Å, b = 8.6125(3) Å, c = 6.8501(2) Å, V = 666.69(4) Å3, Z = 4. The eight strongest reflections in the X-ray powder-diffraction data [d in Å (I) (hkl)] are: 5.65 (100) (200), 4.84 (89) (111), 6.85 (74) (110), 3.06 (56) (112), 3.06 (53) (221), 3.08 (47) (311), 2.68 (28) (022), 2.78 (26) (130). The average chemical composition, determined by quantitative SEM-EDS (N by difference), is (wt%): K2O 3.38, Al2O3 25.35, SO3 36.58, F 26.12, (NH4)2O 22.47, O = F -11.00, total 102.90. The empirical chemical formula, calculated on the basis of 7 anions pfu, is [(NH4)1.85K0.15]Σ2.00Al106F2.94-S0.98O3.06. The crystal structure, determined from single-crystal X-ray diffraction data [R(F) = 0.0367], is characterized by corner-sharing AlF4O2 octahedra which form [001] octahedral chains by sharing two trans fluoride atoms [Al–F2 = 1.8394(6) Å]. Non-bridging Al–F1 distances are shorter [1.756(1) Å]. The two trans oxygen atoms [Al–O = 1.920(2) Å] are from SO4 tetrahedra. NH4+ ions occur in layers parallel to (100) which alternate regularly with (100) layers containing ribbons of corner-sharing AlF4O2 octahedra and associated SO4 groups. The NH4+ ions are surrounded by five oxygen atoms and by four fluorine atoms. The mineral is named as the (NH4)-analogue of thermessaite, K2AlF3(SO4), and corresponds to an anthropogenic phase found in the burning Anna I coal dump of the Anna mine, Aachen, Germany. Both mineral and mineral name have been approved by the IMA-CNMNC commission (IMA 2011-077).
IMA 2011-077 = thermessaite-(NH4)
- 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:
IMA 2011-077 = thermessaite-(NH4)
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:
Re: IMA 2011-077 = thermessaite-(NH4)
Pubblicazione effettuata.
Referenza:
▪ Garavelli, A., Pinto, D., Mitolo, D., Kolitsch, U. (2021): Thermessaite-(NH4), (NH4)2AlF3(SO4), a new fumarole mineral from La Fossa crater at Vulcano, Aeolian Islands, Italy. Mineralogical Magazine, 85, 665-672.
Referenza:
▪ Garavelli, A., Pinto, D., Mitolo, D., Kolitsch, U. (2021): Thermessaite-(NH4), (NH4)2AlF3(SO4), a new fumarole mineral from La Fossa crater at Vulcano, Aeolian Islands, Italy. Mineralogical Magazine, 85, 665-672.
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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