‘Project Airless’ is a three year venture that began in August 2015 at the Natural History Museum (NHM) in London, with the objective of treating and preventing pyrite decay in the Museum’s historic earth sciences collections.
Pyrite, or ‘fool’s gold’ (iron sulphide), is a common mineral of varying crystal structure (though cubic is common) that can often be found in or around fossils. It can occur in a compact, crystallized and stable form – or as a porous, microcrystalline and unstable form.
Pyrite oxidation, or ‘decay’, can occur when the mineral reacts with atmospheric oxygen in relative humidities (RH) above 60%. The resulting by-products of this oxidation depend on the mineral composition of the fossil and matrix, but often comprise sulphuric acid and hydrated ferrous sulphates, which can be very harmful to specimens, labels, and storage media. Once pyrite has begun to oxidise, mineral hydrates will…
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