Phase equilibrium modelling allows us to predict the stable phase assemblage of a rock at equilibrium, in other words the composition and proportion of the rock forming minerals. We can do this if we know the pressure, temperature and bulk composition of the rock. However, many processes that effect the evolution of a crustal rock change its effective bulk composition. Therefore, in order to effectively model crustal processes and differentiation of the continental crust I created a new thermodynamic modelling software tool called Rcrust. I wrote the program and created a graphical user i​nterface to allow user friendly access to its calculations. I have published it is as open source software on both of my institutions' respective websites (https://www.sun.ac.za/english/faculty/science/earthsciences/rcrust); have created a user manual for its teaching and have begun presenting it at seminars at a number of universities. In this way I aim to continue to grow and expand the software's user base while simultaneously growing its functionalities.