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GEOREF RECORD

Opals from Slovakia ("Hungarian" opals); as re-assessment of the conditions of formation

Benjamin Rondeau, Emmanuel Fritsch, Michel Guiraud and Christophe Renac
Opals from Slovakia ("Hungarian" opals); as re-assessment of the conditions of formation
European Journal of Mineralogy (October 2004) 16 (5): 789-799

Abstract

Slovakian opals found in an andesitic host-rock in the Dubnik area, near Kosice (part of Hungary until the end of World War I) are believed to have formed by water circulation during a tectonic event. Their physical properties were investigated by XRD, Raman spectra (main peak at 437 cm (super -1) ) and scanning electron microscope (large silica spheres 125-270 nm in diameter). Surprisingly, these are properties of opals usually found in sedimentary deposits rather than those found in opals of volcanic rocks. Some preliminary results of a study of their oxygen isotopes indicate a high delta (super 18) O for Slovakian and Australian opals (310/00), consistent with temperatures of formation < 45 degrees C; in contrast, Mexican opal-CT shows a lower delta (super 18) O of 130/00 consistent with formation at a higher T, possibly as high as 190 degrees C.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 16
Serial Issue: 5
Title: Opals from Slovakia ("Hungarian" opals); as re-assessment of the conditions of formation
Affiliation: Museeum National d'Histoire Naturelle, Departement Histoire de la Terre, Paris, France
Pages: 789-799
Published: 200410
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 57
Accession Number: 2004-084047
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
N47°45'00" - N49°40'00", E16°49'00" - E22°30'00"
Secondary Affiliation: Institut des Materiaux Jean Rouxel, FRA, FranceUniversite Jean Monet, FRA, France
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 200424
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