Diffraction contrast tomography: unlocking its potential for mineral resources application

Laboratory Diffraction Contrast Tomography (LabDCT) is an emerging 3D non-destructive characterisation technique that has been widely utilised in materials science but remains relatively novel in geoscience. This research illustrates its potential for complex natural materialsthrough applications to chromite sands, chromitite from the Bushveld Complex, and other geomaterials such as olivine, rock salt, and diopside. By comparing identical 2D slices from LabDCT with EBSD results, our findings demonstrate good agreement, with average disorientation angles between DCT and EBSD consistently within 0.3° (Chen et al., 2023). This comparison validates the accuracy and reliability of LabDCT. Furthermore, LabDCT uniquely provides comprehensive 3D data, including volumetric and textural information, offering deeper insights into igneous and metamorphic processes that are beyond the reach of traditional 2D methods.

To address artefacts such as inaccurate grain boundaries and partially indexed grains, we developed a novel post-processing workflow validated through comparisons with EBSD data (Chen et al., 2024). This workflow refines grain boundary definitions, improves reconstructions of partially indexed grains, and rectifies morphological inaccuracies. Results from both resin-mounted chromite and natural chromitite samples demonstrated a significant enhancement in the accuracy of LabDCT outputs, not only reducing unindexed volumes but also restoring precise crystallographic data.

This research demonstrated the application of LabDCT to a series of natural rocks, underscoring LabDCT’s revolutionary potential in mineralogy. Its capabilities are particularly valuable to understand the genesis of ore deposits, advancing the recovery of critical metals, and assessing rock textures in 3D.

 

References

Chen, X., Godel, B., & Verrall, M. (2023). Comparison of Laboratory Diffraction Contrast Tomography and Electron Backscatter Diffraction Results: Application to Naturally Occurring Chromites. Microscopy and Microanalysis, 29 (6), 1901-1920.

Chen, X., Godel, B., & Verrall, M. (2024). Postprocessing Workflow for Laboratory Diffraction Contrast Tomography: A Case Study on Chromite Geomaterials. Microscopy and Microanalysis, 30 (3), 440-455.