The hierarchical internal structure of "labradorite"

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Marco E. Ciriotti
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The hierarchical internal structure of "labradorite"

Messaggio da Marco E. Ciriotti » mer 28 set, 2022 9:57

Referenza:
▪ Götz, E., Kleebe, H.J., Kolb, U. (2022): The hierarchical internal structure of labradorite. European Journal of Mineralogy, 34, 393–410.

Abstract:
The different structural features of labradorite and its incommensurate atomic structure have long been in the eye of science. In this transmission electron microscopy (TEM) study, all of the structural properties of labradorite could be investigated on a single crystal with an anorthite–albite–orthoclase composition of An53.4Ab41.5Or5.1. The various properties of labradorite could thus be visualized and connected to form a hierarchical structure. Both albite and pericline twins occur in the labradorite. The size of alternating Ca-rich and Ca-poor lamellae could be measured and linked to the composition and the color of labradorescence. Furthermore, a modulation vector of 0.0580(15)a* + 0.0453(33)b* − 0.1888(28)c* with a period of 3.23 nm was determined. The results indicate an eα labradorite structure, which was achieved by forming Ca-rich and Ca-poor lamellae. The average structure and subsequently the incommensurate crystal structure were solved with a three-dimensional electron diffraction (3DED) data set acquired with automated diffraction tomography (ADT) from a single lamella. The results are in good agreement with the structure solved by X-ray diffraction and demonstrate that 3DED–ADT is suitable for solving even incommensurate structures.
Marco E. Ciriotti

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

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Massimo Russo
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Re: The hierarchical internal structure of "labradorite"

Messaggio da Massimo Russo » mer 28 set, 2022 10:30

Ma perché si continua a parlare di labradorite se l'IMA l'ha eliminata?

Massimo
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Massimo Russo
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Marco E. Ciriotti
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Re: The hierarchical internal structure of "labradorite"

Messaggio da Marco E. Ciriotti » mer 28 set, 2022 10:41

Nello specifico perché questo membro intermedio tra albite e anortite ha una sua specifica struttura cristallina.
Marco E. Ciriotti

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