Diamond growth by sulphide reduction of CO2

Abstract

MARX1 proposed that natural diamonds were formed by a reduction of CO2 and other theories have been proposed to explain their formation2-6. Carbon dioxide is a common constituent7,8 and has been found as a gas in natural diamonds9. Marx proposed that pyrrhotite is active in the reduction process because it has been found as an inclusion in diamonds10. Furthermore, thermodynamic calculations showed such a reduction reaction to be energetically possible: "figure presented". © 1974 Nature Publishing Group.