NRA analyses of N and C in hydromuscovite aggregates from a 3.5Â Ga chert from Kittys Gap, Pilbara, Australia

Biophile elements nitrogen and carbon were found in hydromuscovite aggregates of an Archean chert from Kittys Gap, W. Australia, hosting probable evidence of life. Their concentrations do not show a linear relationship, as expected if they where produced by a common organic source. The lack of a linear relationship is related to N and C fractionation at the mineral scale. N occurs in the form of NH4+, tightly retained at the K+ lattice sites, while C could occurs as a dispersed organic phase in hydromuscovite aggregates or in a weakly bounded form, possibly HCO3-.