Fool's gold, fool's paradise? Utilising X-ray micro-Computed Tomography to evaluate the effect of environmental conditions on the deterioration of pyritic fossils

Abstract

Natural history museums hold hundreds of thousands of mineral and fossil specimens containing iron sulfides, such as pyrite, all of which may be at risk from deterioration. Oxidation of these minerals causes cracking, crystal growth and powdering which, if unchecked, can eventually lead to the complete loss of specimens. This article reports the findings of an experiment which utilised X-ray micro-Computed Tomography (μCT) to generate 3D time lapse imaging over 15 months to compare the deterioration of pyritic ammonites stored within micro-environments created with varying levels of oxygen and relative humidity. The study concludes that the optimum storage parameters for the preservation of sulfide-bearing specimens are 40% relative humidity and 0% oxygen.