J 2022

Structural Breakdown of Natural Epidote and Clinozoisite in High-T and Low-P Conditions and Characterization of Its Products

KOZÁKOVÁ, Petra, Marcel MIGLIERINI, Mária ČAPLOVIČOVÁ, Radek ŠKODA, Peter BAČÍK et. al.

Základní údaje

Originální název

Structural Breakdown of Natural Epidote and Clinozoisite in High-T and Low-P Conditions and Characterization of Its Products

Autoři

KOZÁKOVÁ, Petra, Marcel MIGLIERINI, Mária ČAPLOVIČOVÁ, Radek ŠKODA (203 Česká republika, domácí) a Peter BAČÍK (garant)

Vydání

Minerals, MDPI, 2022, 2075-163X

Další údaje

Jazyk

angličtina

Typ výsledku

Článek v odborném periodiku

Obor

10504 Mineralogy

Stát vydavatele

Švýcarsko

Utajení

není předmětem státního či obchodního tajemství

Odkazy

Impakt faktor

Impact factor: 2.500

Kód RIV

RIV/00216224:14310/22:00125601

Organizační jednotka

Přírodovědecká fakulta

UT WoS

000771464500001

Klíčová slova anglicky

epidote; clinozoisite; heat treatment; structure breakdown; esseneite

Štítky

Příznaky

Mezinárodní význam, Recenzováno
Změněno: 1. 4. 2022 09:50, Mgr. Marie Šípková, DiS.

Anotace

V originále

A heat treatment was performed on selected epidote and clinozoisite crystals to establish the nature of any changes in the optical and crystal-chemical properties and to identify a breakdown product using a wide spectrum of analytical methods. Natural samples were heated from 900 to 1200 °C under atmospheric pressure in ambient oxidation conditions for 12 h. Epidote and clinozoisite were stable at 900 °C; those heated at 1000 °C, 1100 °C, and 1200 °C exhibited signs of breakdown, with the development of cracks and fissures. The average chemical composition of epidote is Ca2.000Al2.211Fe0.742Si2.994O12(OH), while that of clinozoisite is Ca2.017A12.626Fe0.319Si3.002O12(OH). The breakdown products identified by electron microanalysis, powder X-ray diffraction, Raman spectroscopy, and high-resolution transmission electron microscopy were anorthite, pyroxene compositionally close to esseneite, and wollastonite. The decomposition of the epidote-clinozoisite solid solution is controlled by the following reaction: 4 epidote/clinozoisite → 2 pyroxene + 2 wollastonite + 4 anorthite + 2 H2O. Pyroxene likely contains a significant proportion of tetrahedral Fe3+ as documented by the Mössbauer spectroscopy. Moreover, the presence of hematite in the Mössbauer spectrum of the clinozoisite sample heated at 1200 °C can result from the following reaction: 4 epidote → pyroxene + 3 wollastonite + 4 anorthite + hematite + 2 H2O.