Luke Hilchie

Diamond dissolution experiments in Cl-H₂O fluids produce distinctive resorption features on diamonds and reveal insights into diamond oxidation mechanisms, with implications for kimberlitic and mantle fluids. Experiments at 1350^oC and 1 GPa show that chloride-rich aqueous fluids produce few edge dissolution features and abundant trigons on octahedron faces. Deep etch channels form within some trigons. These features occur naturally and have not previously been produced experimentally, implying that natural diamonds with etch channels may have been dissolved in chlorite-rich fluid. The formation of etch channels within trigons supports a defect-related origin of these features. Reduction of edge dissolution in chlorite-rich aqueous fluid may result from cations blocking electron-dense diamond edges and vertices, preventing polar water molecules from preferentially dissolving these sites. This interpretation provides an explanation for previously observed face-dominated dissolution features produced in CO₂ fluid. Future experiments will explore diamond dissolution in Cl-CO₂ fluids and the effect of other polar and non-polar solvents on diamond dissolution features. Comparison of experimental results to natural diamonds may elucidate the importance of chloride in kimberlitic or mantle fluids.

Keywords:
Pages: 71
Supervisor: Yana Fedortchouk