When synthesised at high pressure and temperature, holmium germanate adopts the pyrochlorestructure. Because of its geometry, materials with this structure often have exotic and interestingmagnetic properties. Normally, the pyrochlore structure is only stable when the two metals arerelatively similar in size, which is not the case for Ho and Ge. This explains why extremeconditions are required to make it. In this experiment we will use the Pearl diffractometer to followthe conversion of a mixture of the simple component oxides to the pyrochlore as we increasetemperature and pressure. We have also recently made a sample of holmium germanate in adifferent crystal structure and hope to use this as a precursor phase that can be converted to thepyrochlore at lower temperature or pressure than the simple oxide approach.