A demonstration of an affinity between pyrite and organic matter in a hydrothermal setting

An important requirement for the origin of life is the concentration of organic compounds to allow interaction with each other and with other chemical species. An efficient mechanism for concentrating organic molecules is the adsorption onto mineral surfaces. There are several examples of minerals with strong affinities for the accumulation of organic matter. These include for instance clays [1], radioactive minerals [2], zeolites and feldspars [3] and sulphide minerals including pyrite (FeS2) [4,5].Here, we study the relationship between pyrite and migrated organic matter in the geological record, via hydrothermal deposits of the Irish Carboniferous, to assess the potential of pyrite acting as a substrate for organic matter.The iron-sulphur world hypothesis for the origin of life was proposed by W？chtersh？user [5]. He suggests that the formation of pyrite (FeS2) is the first energy source for life. The iron-sulphur world takes place in a hydrothermal setting, where iron- and sulphur-rich water produces abundant pyrite deposits. The formation of pyrite releases energy that could have been utilized during an autotrophic setting for the origin of life. The iron-sulphur world scenario for the origin of life stands in contrast to the heterotrophic origin of life in the "cold soup" theory [6,7]. In addition to an autotrophic origin of life, the iron-sulphur world also proposes pathways for the origin of cell membranes, the origin of DNA, and a range of other biochemical reactions essential to the origin of life [8].A key-aspect of the iron-sulphur world theory is the adsorption of organic molecules to the surface of pyrite. The theory predicts that since the surface of pyrite is slightly positively charged, it would attract and bind negatively-charged organic molecules. The organic molecules would be connected to the surface of pyrite with weak ionic bonds, and therefore able to migrate rather freely around the surface of the pyrite crystal. This would make them more lik