High PT properties of breyite, larnite and titanite

We propose to measure the crystallographic properties of breyite (CaSiO3, previously known as walstromite), larnite (Ca2SiO4) and titanite (CaSi2O5) as a function of temperature from ~ 5-12 GPa. These three calcium-rich phases are commonly observed in diamond-hosted inclusions, and in this context are often believed to be the exhumation breakdown products of former calcium perovskite minerals. This hypothesis could be more rigorously tested if the structure and high PT equation of state (EoS) of these minerals were known, allowing entrapment conditions to be reliably estimated from observed remnant pressures. Our results will significantly enhance interpretations of the formation and exhumation history of superdeep diamonds and their inclusions.