What is mc_fit?

• It is a Perple_X [Connolly2009] program based on the algorithm of Khan et al. [Khan2021] for inverting natural and experimental phase equilibria to estimate thermobarometric conditions (Slides 19-22) and/or unknown thermodynamic parameters (Slides 23-25, [Pitsch2025]).

• It works by finding the best match between observations and a thermodynamic model of the observations predicted by free energy minimization as a function of the unknown parameters (i.e., the inversion parameters).

• It can propagate analytical and thermodynamic parameter uncertainties to evaluate the uncertainty of the inversion parameters.

• It does not require complete compositional information; it can invert for unmeasured properties such as ferric-ferrous ratio and volatile content.

• It can incorporate bulk compositional and modal constraints when available, but does not require them.