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Agate; a study of ageing

Terry Moxon
Agate; a study of ageing
European Journal of Mineralogy (December 2002) 14 (6): 1109-1118


The degree of crystallinity in wall-lining agates from host rocks of varying ages has been measured using XRD. A plot of agate crystallite size vs log age of host rock shows a general increase in crystallite size with increasing age of the host rock: a regression line: size = 106 log host rock + 211 was obtained. The SEM confirms that ageing produces a growth in the surface globulites and development of plate edge-like structures within the white bands. This dynamic growth of crystallites results in an increase in density. A high correlation between agate crystallite size and age of the host rock shows that the formation of wall-banded agates is penecontemporaneous with the formation of the host rock. The determination of crystallite size in such agates allows either an estimation of the approximate age of the host rock or an identification of a known agate region.

ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 14
Serial Issue: 6
Title: Agate; a study of ageing
Author(s): Moxon, Terry
Affiliation: 55 Common Lane, Auckley, United Kingdom
Pages: 1109-1118
Published: 200212
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 44
Accession Number: 2003-006881
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 200302
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