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@article{1844297,
author = {Kozáková, Petra and Miglierini, Marcel and Čaplovičová, Mária and Škoda, Radek and Bačík, Peter},
article_number = {2},
doi = {http://dx.doi.org/10.3390/min12020238},
keywords = {epidote; clinozoisite; heat treatment; structure breakdown; esseneite},
language = {eng},
issn = {2075-163X},
journal = {Minerals},
title = {Structural Breakdown of Natural Epidote and Clinozoisite in High-T and Low-P Conditions and Characterization of Its Products},
url = {https://www.mdpi.com/2075-163X/12/2/238},
volume = {12},
year = {2022}
}
TY - JOUR
ID - 1844297
AU - Kozáková, Petra - Miglierini, Marcel - Čaplovičová, Mária - Škoda, Radek - Bačík, Peter
PY - 2022
TI - Structural Breakdown of Natural Epidote and Clinozoisite in High-T and Low-P Conditions and Characterization of Its Products
JF - Minerals
VL - 12
IS - 2
SP - 1-19
EP - 1-19
PB - MDPI
SN - 2075163X
KW - epidote
KW - clinozoisite
KW - heat treatment
KW - structure breakdown
KW - esseneite
UR - https://www.mdpi.com/2075-163X/12/2/238
N2 - 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.
ER -
KOZÁKOVÁ, Petra, Marcel MIGLIERINI, Mária ČAPLOVIČOVÁ, Radek ŠKODA a Peter BAČÍK. Structural Breakdown of Natural Epidote and Clinozoisite in High-T and Low-P Conditions and Characterization of Its Products. \textit{Minerals}. MDPI, 2022, roč.~12, č.~2, s.~1-19. ISSN~2075-163X. Dostupné z: https://dx.doi.org/10.3390/min12020238.
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