Mineral inclusions in diamonds from the mantle transition zone

During crystallisation, a small proportion of diamonds (no more than 2%), captures tiny inclusions of other minerals. These mineral inclusions sometimes derive from great depths and are our only window into the Earth’s transition zone (410-660 km) and the lower mantle (660-2900 km), regions of our planet, impossible to sample directly. We have two large (>3 mm) rare diamonds from the mantle transition zone to lower mantle depths with around 20 inclusions. Our preliminary study suggests that some of the minerals inside may be new, never discovered before. In this proposal, we will combine phase contrast tomography (PCT), single-crystal diffraction, scanning 3DXRD and X-ray fluorescence to pin-point different inclusions in the diamond and identify their crystal structures, morphologies, compositions and possible paragenesis (characteristic co-existence of different minerals). As a result, we plan to discover new minerals in addition to improving our understanding of the Earth's mantle.