Chaleux

Notches in the iron sulphide nodules of the Chaleux cave indicate their use as a lighter. Th eir mineralogy was compared with other fi broradiated
nodules, more particularly coming from the Cap Blanc-Nez (France). Only pyrite rather than marcasite was identifi ed by X-ray diff raction. Nodules
are composed of a core of fi broradiated pyrite and an external rim of goethite, probably acquired in the geological environment. Th e human-made notch
also exhibits a rim of goethite linked with the pyrite oxidation in the archaeological deposit. Under new physicochemical conditions prevailing in the
conservatories, one of the exhumed nodules disintegrated as a result of the crystallization of complex secondary iron sulfates. Th e primary and secondary
minerals from lighters and comparative material were determined by X-ray diff raction, scanning electron microscopy and energy dispersive spectroscopy.
Prevailing chemical reactions are self-sustaining causing the total destruction of the material. Th e paragenesis changes over time depending on changes in
physicochemical parameters. Preservation of artifacts and samples of pyrite or marcasite demands to prevent contact between the sulphides and moist air.
Diff erent methods exist but none of them is completely reliable.