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THE ORIGIN, DESTRUCTION AND RESTORATION OF COLOUR IN EGYPTIAN TRAVERTINE *
Author(s) -
HARRELL J. A.,
BROEKMANS M. A. T. M.,
GODFREYSMITH D. I.
Publication year - 2007
Publication title -
archaeometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.716
H-Index - 67
eISSN - 1475-4754
pISSN - 0003-813X
DOI - 10.1111/j.1475-4754.2007.00312.x
Subject(s) - calcite , sunlight , ultraviolet , mineralogy , irradiation , ultraviolet light , ultraviolet irradiation , geology , chemistry , photochemistry , optics , physics , nuclear physics
Travertine was one of ancient Egypt's most popular ornamental stones. Upon prolonged exposure to sunlight, the rock's translucent brownish calcite is bleached to nearly white. Ultraviolet and gamma irradiation experiments were undertaken to investigate the source of the brownish colour and the process by which it fades. It was found that the coloration results from the activation of colour centres by natural radioactivity within the rock, and that these colour centres are deactivated by the ultraviolet component of sunlight. The results also demonstrate that the original brownish colour of sun‐bleached, travertine objects can be restored by artificial gamma irradiation.