A thermal study of the new mineral belomarinaite

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Marco E. Ciriotti
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Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy

A thermal study of the new mineral belomarinaite

Messaggio da Marco E. Ciriotti » lun 22 mar, 2021 14:04

▪ Belousova, M.G., Saprykina, O.Yu., Bubnova, R.S., Shablinskii, A.P., Vergasova, L.P., Belousov, A.B., Filatov, S.K. (2021): A Thermal Study of the New Mineral Belomarinaite KNaSO4. Journal of Volcanology and Seismology, 15, 51-57.

For the first time, the thermal behavior of a new mineral belomarinaite KNaSO4 from volcanic exhalations (trigonal crystal system, Sp. gr. P3m1, a = 5.6072(3), c = 7.1781(4) Å, V = 195.45(2) Å3) was studied on a natural sublimate sample from the 2012–2013 Tolbachik Fissure Eruption and its synthetic analogue, a low temperature (LT) polymorph of (Sp. gr. P3m1) in the range 30–800°C (high-temperature X‑ray diffraction) and 30–1000°C (DSC and TG). The mineral is stable up to a temperature of 470 ± 5°C, at which it has a polymorphic transformation into a high-temperature (HT) hexagonal polymorphic modification (Sp. gr. P63/mmc), which is stable until melted at 840°C based on DSC. The thermal expansion of both modifications is sharply anisotropic, and in the case of the HT phase the parameter a has a U-shape dependence with a minimum at T = 620°C. The volumetric expansion of the αV HT phase is greater than that for the LT phase by factors of 2–2.5 on average.
Marco E. Ciriotti

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