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.