P-T-X Constraints on Ilmenite Unit Cell and Relationship to Kimberlitic and Non-Kimberlitic Sources
Abstract
This research investigates the mineral ilmenite, focusing on the relationship between crystal structure and geochemical and/or pressure data. Ilmenites were obtained from diamond-rich and diamond-poor kimberlites and non-kimberlitic localities, to discriminate between these populations. Crystallographic results showed a delineation between kimberlitic and non-kimberlitic ilmenites at a c-axis value of 14.02 (±0.01) Å. Adding geochemistry and pressure enhances the separation of kimberlitic and non-kimberlitic samples; however, this isn’t the case for diamond-rich versus diamond-poor kimberlites, even with three-dimensional and cluster analyses. A subset of kimberlitic ilmenites (manganese rich) were found with c-axis values and geochemical concentrations similar to non-kimberlitic ilmenites.
By reanalyzing ilmenite samples from previous theses, reinterpretation of complexities in the past data could be done, and a measure of reliability could be determined. The 14.02 (±0.01) Å c-axis unit cell value seems consistent, enabling X-ray diffraction to potentially be used as an alternative to geochemical methods for diamond exploration.