On the Variations in the Relative Abundance of the Carbon Isotopes in Carbonate Minerals

The ratio $$C^{12}/C^{13}$$ for forty-five samples of eleven carbonate minerals has been measured. The ratios of dolomites are all under 89, the ratios of carbonates from the oxidation zone of ores are all over 89, and the ratios of other carbonate minerals are distributed over a greater range. The distribution of the carbon isotope ratios is discussed with special reference to the genetic relationships, and the results are shown to be in agreement with theoretical considerations.