Pyrite in fossils

Michael Maus <m.maus [at] geo__uni-mainz__de> writes

>I have severe problems with fossils from the rheinish-slate
>mountains in Germany. The fossils are usually preserved as pyrite
>(iron-sulfide) ...
>... Because of high air-humidity the pyrite started to decay
>...
>After the treatment I want to protect the specimens from further
>decay by impregnating them. ...
>.. are there
>better ways to conserve pyrite?

As one of the authors of the paper 'Use of Ethanolamine
Thioglycollate in The Conservation of Pyritised Fossils
(Palaeontology vol 27 part 2 1984 pp 421-424) I am happy to send
copies of the paper to any interested party. The technique has been
very successful on a variety of actively decomposing pyritic
specimens (both dry and fluid preserved) and alongside an
alternative treatment devised by Rob Waller 'An Experimental Ammonia
Gas Treatment For Oxidised Pyrite  (National Museum of Natural
Sciences, Ottawa, Canada) is effective for already damaged material.

However, my main experience suggests that prevention is better than
cure; by maintaining a low humidity (lower than 40%) the probability
of pyrite breakdown occurring is significantly decreased. The use of
microclimates is an effective way of preventing damage in a diverse
collection without full-scale humidity control.

I also recommend that even after treatment, all treated material is
kept in a low humidity to prevent further 'outbreaks'. This may be
due to the inability of the treatments to neutralise and/or remove
any of the remaining actively decaying microcrystalline pyrite.

A research project (unpublished) conducted in 1996 at The Natural
History Museum Palaeontology Department (London, England) of over
500 specimens treated for pyrite oxidation, provided us with data
suggesting that the Ethanolamine Thioglycollate treatment was
effective although lack of detailed records makes long term
assessment extremely difficult.

Mr Adrian M Doyle
Conservation Scientist
Palaeontology Conservation Unit
Department of Palaeontology
The Natural History Museum
Cromwell Road
London SW7 5BD
U.K.
+44 20 7942 5116
Fax: +44 20 7942 5546


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                  Conservation DistList Instance 15:43
                 Distributed: Monday, December 17, 2001
                       Message Id: cdl-15-43-008
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