Fig. 6.

(a) Chromium three-isotope diagram showing the artificial mass-independent μ⁵⁴Cr* and μ⁵³Cr* anomalies resulting from equilibrium mass-dependent isotope fractionation (e.g. induced through equilibrium isotope partitioning between Cr(III)-species), corrected using the commonly used kinetic fractionation law. This amounts to 7.3 and 2.8 ppm artificial μ⁵⁴Cr* and μ⁵³Cr* anomaly, respectively, for every 100ppm/amu equilibrium mass-dependent fractionation. (b) The typical analytical precision on μ⁵⁴Cr* and μ⁵³Cr* limits the magnitude of such mass-dependent stable isotope fractionation to less than 80–180ppm μ⁵⁴Cr* is used to infer ⁵⁴Cr nucleosynthetic variability in primitive meteorites, whereas μ⁵³ Cr* excesses (if correlating with Mn/Cr) is a proxy for radiogenic⁵³Cr ingrowth from short-lived ⁵³Mn decay.