Synthesising rock and mineral equivalents at high temperatures and pressures is a little bit like baking, causing particular excitement when the run product turns out differently than expected. I will present a range of combined experimental mineralogy and mineral analysis (SEM, XRD) studies that increased our understanding of natural systems by investigating the interdependence of chemical composition and crystal structure. I will talk about geothermobarometry using the mineral titanite, phase diagrams, solid solutions and the mineral srilankite, new compounds I made along the way, the surprise discovery of the mineral dolomite in living coralline algae, and how dirty goethite and hematite in Pilbara iron ore are crying out for synthetic counterparts.