XRD investigations in geological and mineralogical fields

Importance of the Topic

Understanding the mineralogical composition of geological materials is fundamental for disciplines ranging from academic research to resource exploration and quality control in industry. X-Ray diffraction (XRD) offers a reliable, non-destructive method to identify and quantify crystalline phases in rocks, sediments and soils. By capturing unique diffraction patterns, XRD helps characterize lattice parameters and mineral fingerprints, guiding decision-making in environmental studies, mining and material science.

Objectives and Study Overview

This article presents a practical guide to applying benchtop XRD analysis in geological and mineralogical investigations. It outlines sample preparation, instrumentation requirements, data acquisition protocols and analytical workflows, using the Thermo Scientific ARL™ X’TRA Companion system as a case study. Emphasis is placed on phase identification, quantification via Rietveld refinement and the complementarity of XRD with X-Ray fluorescence (XRF).

Methodology and Instrumentation

The ARL X’TRA Companion is a compact θ/θ Bragg-Brentano diffractometer equipped with a 600 W Cu or Co source, mechanical and Soller slits, and a high-resolution semiconductor pixel detector (55 × 55 µm). Sample holders accommodate powders or solids, with optional automated sample changers for high throughput. Open-source software (PROFEX) interfaces with ICDD or COD databases for phase matching, while MATCH!, MAUD or FULLPROF enable Rietveld-based quantification.

Sample Preparation

Rock specimens are crushed and milled to ~100 µm to ensure representative sampling. Powder is loaded into holders with care to minimize preferred orientation, especially for platy minerals like clays. Prepared samples yield reproducible diffraction profiles within short acquisition times.

Main Results and Discussion

XRD patterns reveal peaks corresponding to magnetite, quartz, annite, sekáninaite, anorthite, oligoclase and siderite. Rietveld analysis provides weight percentages: quartz (~52.6 %), magnetite (~15.5 %), anorthite (~15.3 %) and minor phases. Iron speciation is also determined, giving total Fe at ~13.8 wt % with Fe3+/Fe2+ ratios of ~7.5 / 6.4 wt %. These results demonstrate the instrument’s ability to resolve complex mineral assemblages and quantify redox states.

Practical Benefits and Applications

• Rapid phase identification and quantification for exploration geology and environmental monitoring.
• Automated workflows reduce operator intervention and integrate with LIMS for large sample batches.
• High-resolution detector ensures precise lattice parameter determination and trace phase detection.
• Complementary use with XRF enhances compound versus elemental analysis, improving overall characterization fidelity.

Future Trends and Opportunities

Advances in microdiffraction and in situ high-temperature/pressure stages will expand applications to micro-scale domains and real-time phase transformations. Integration with machine learning algorithms for automated phase recognition and refinement promises faster insights. Portable and field-deployable XRD systems may bring crystallographic analysis directly to exploration sites.

Conclusion

The Thermo Scientific ARL X’TRA Companion benchtop XRD delivers robust, high-quality mineralogical data suited for both academic and industrial geoscience. Its combination of ease-of-use, automation and open-source software support makes it an essential tool for efficient phase analysis and quantification. Pairing XRD with complementary techniques such as XRF further enriches material characterization.

Instrumentation Used

• Thermo Scientific ARL™ X’TRA Companion θ/θ Bragg-Brentano XRD system
• 600 W Cu or Co X-ray source
• Semiconductor pixel detector (55 × 55 µm)
• Open-source PROFEX, MATCH!, MAUD/FULLPROF software
• ICDD and COD crystallographic databases