Thanks to Hugh Jarvis on the Lithics-L list (lithics-l@listserv.buffalo.edu) for drawing attention to the new edition of Archaeometry [49(3), August 2007]. As well as a fascinating list of titles on other subjects, there is a paper that concerns Egyptology.
The origin, destruction and restoration of colour in Egyptian travertine. By J.A. Harrell, M.A.T.M., Brekmans, and D.I. Godrey-Smith. Page 421
Abstract:
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.
Abstracts can be read free of charge on the Archaeometry website, but to view the entire article you either need to subscribe to the journal or pay $29.00 (USD) for a 30 day online access to the article.
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