Like other perovskite minerals, calcium silicate perovskite (capv) undergoes a series of subtle crystallographic phase transitions with temperature (and pressure). These tiny symmetry changes in capv are associated with disproportionately large elastic anomalies. However, variability within existing estimates of the slope of capv’s phase transitions prevent them from being used to interpret mantle seismological observations. We propose to study the crystallography of capv at conditions up to at least 50 GPa and 2000 K in the large volume press on ID06 by using sintered diamond anvils for pressure generation. ID06-LVP is the only global setup with proven diffraction resolution to unambiguously identify phase transitions of capv, and thus provides an unparalleled opportunity to investigate the explanation for seismic heterogeneities throughout the Earth’s deep mantle.