The equilibrium partitioning of stable isotopes among coexisting mantle minerals can be used as a tool for geochemists to learn about the conditions of formation and subsequent alteration of mantle rocks.

Mantle xenolith from San Carlos, AZ

High temperature and pressure experiments using a piston- cylinder apparatus allow us to determine what the equilibrium fractionation values are for different stable isotope systems at mantle conditions.

These values can then be compared to measurements of the isotope values in natural minerals from mantle xenoliths to gain insight into the petrogeneses of these rocks, and the processes that may affect them deep inside the Earth, such as partial melting and metasomatism.

Secondary electron image of spinel (small octahedra) and olivine crystals grown in an isotope exchange experiment on the piston-cylinder at 800 °C and 10 kbar.

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