The effect of the mineral matter on the reactivity of a coke analogue was examined through the addition of binary and ternary combinations of magnetite (Fe3O4), troilite (FeS) and quartz (SiO2). The use of coke at a laboratory scale has issues arising from it heterogeneity and complex nature. The coke analogue was developed to help alleviate these issues, being a laboratory tool that has a simplified carbon structure and in which the mineral content, particle size and distribution is largely controlled. The reactivity of the coke analogue with CO2 was measured using a TGA system at 1100°C under conditions similar to that of the CRI test. For binary combinations of magnetite-quartz and troilite-quartz, increasing quartz content (and subsequently decreasing the iron content) was found to decrease the reactivity of the coke analogue. The change in the reactivity of the troilite-magnetite binary system was found not to be simply additive, with combinations of troilite and magnetite giving higher reactivities than would be expected from a simple proportional approach. The ternary magnetite-troilite-quartz system was found to largely follow the trends found in the bounding binary systems.