Natisite: occurrence, crystal chemistry and genetic features

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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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Natisite: occurrence, crystal chemistry and genetic features

Messaggio da Marco E. Ciriotti » lun 05 lug, 2021 11:15

Referenza:
▪ Pekov, I.V., Zubkova, N.V., Chukanov, N.V., Yapaskurt, V.O., Turchkova, A.G., Ksenofontov, D.A., Pushcharovsky, D.Yu. (2021): Natisite, an indicator mineral of hyperagpaitic hydrothermal assemblages in Lovozero and Khibiny alkaline intrusions (Kola Peninsula): occurrence, crystal chemistry and genetic features. Zapiski RMO, 150(3), 1-26.

Abstact:
Natisite, a natural tetragonal (P4/nmm) modification of Na2TiSiO5 = Na2TiO(SiO4) is a widespread, indicator mineral of relatively low-temperature (not higher than 300–350 °C) peralkaline (hyperagpaitic) hydrothermal assemblages in the Lovozero and Khibiny alkaline intrusions (Kola Peninsula, Russia). Natisite amount in the hypersodic (with Na >>K) hydrothermal veins in Lovozero is up to 30 vol. % and in the hydrothermally altered zones of potassium-rich in Khibiny it is up to 10 vol. %, i.e. natisite can be a rock-forming mineral, the major concentrator of Ti in the rock. In Lovozero natisite is a primary mineral directly crystallized from the hydrothermal solution, whereas in Khibiny natisite mineralization has secondary character: the major amount of natisite occurs in pseudomorphs after earlier Ti minerals, namely ilmenite, titanite, aenigmatite, lamprophyllite and rinkite. Natisite demonstrates stable chemical composition typically close to Na2TiSiO5. A very bright blue to bluish-white fluorescence in shortwave ultraviolet light (λ = 245 nm) is an important diagnostic feature of natisite. The crystal structure of natisite was first solved for the natural sample (Mt. Rasvumchorr, Khibiny), R1 = 1.97%. The comparative study of natisite and other titanosilicates with tetragonal pyramids TiO5 showed the clear negative correlation between length of essentially covalent bond Ti–O in titanyl group and frequency of its stretching vibrations in the IR spectrum.
Marco E. Ciriotti

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

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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: Natisite: occurrence, crystal chemistry and genetic features

Messaggio da Marco E. Ciriotti » lun 13 feb, 2023 13:45

Anche in:

▪ Pekov, I.V., Zubkova, N.V., Chukanov, N.V., Yapaskurt, V.O., Turchkova, A.G., Ksenofontov, D.A., Pushcharovsky, D.Yu. (2022): Natisite, an indicator mineral of hyperagpaitic hydrothermal assemblages in Lovozero and Khibiny alkaline intrusions (Kola Peninsula): occurrence, crystal chemistry and genetic features. Geology of Ore Deposits, 64, 452-469.
Marco E. Ciriotti

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

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