Mineral impurities and their traceability along the graphite value chain

Mineral impurities and their traceability along the graphite value chain

G. Obbágy1*, R. Arató1, Z. Dallos1, F. Melcher

1 Technical University of Leoben, Chair of Geology and Economic Geology, 8700 Leoben, Austria,
e-mail: [email protected]


Graphite is a critical raw material essential for the energy transition, most commonly used as an anode material in lithium-ion batteries. In the Critical Raw Materials Act, the European Union seeks to diversify raw material imports and aims for at least 10% of its annual consumption to originate from domestic mines by 2030. However, there is currently no standardized method to trace or differentiate between sources of natural graphite.
Graphite ore is extracted from diverse geological environments. The ore is crushed and floated onsite, resulting in concentrates with approximately 95% purity that are traded globally. Our goal is to develop a fingerprinting method for major natural graphite deposits by identifying material characteristics that remain traceable along at least part of the value chain. In-situ analytical techniques (e.g., LA-ICP-MS and LIBS) reveal a wide range of detectable elements in spatially restricted areas, indicating separate phases as the source of chemical differences between samples (ARATÓ et al. 2025). However, it remains unclear what these phases are and whether they stay traceable throughout the value chain.
In this study, a sedimentary provenance analysis approach was applied to identify the source region of graphite concentrates. Phases with a density greater than graphite's were separated using heavy liquid (ẟ=2.46 g/cm³) to enhance the mineralogical signal of each locality. These mineral impurities were embedded in epoxy for easier measurement. For morphological and chemical analysis, an SEM-EDS system (Carl Zeiss SmartPI™) was used. Each phase type was verified using Raman spectroscopy, and a database was created for automatic phase identification. The most common mineral impurities in the graphite concentrates include quartz, mica, plagioclase, and iron oxides; at some localities, amphiboles, pyroxenes, talc, apatite, titanite, and sulfides are also found. The main phases detected align well with X-ray diffraction results from bulk graphite concentrates. Additionally, high-resolution transmission electron microscopy revealed the size and nature of the mineral impurities. Most minerals are adsorbed on the surface of graphite flakes, while sheet silicates are often intergrown with graphite. The mineral sizes range from a few nanometers to millimeters.
For battery-specific applications, graphite concentrates are purified using alkali-autoclave leaching and/or hydrofluoric acid treatment to achieve a minimum purity of 99.95%. These purified samples were also subjected to the density separation and analytical protocol described above. As a result of chemical purification, some mineral phases are completely removed, reducing the relative mineral impurity ratio. Conversely, the more resistant mineral phases (e.g., titanite, rutile, zircon) become enriched in the “heavy” fraction, allowing traceability along the value chain.
This study was funded by the European Union under grant agreement no. 101091502, project MaDiTraCe – Material and Digital Traceability for the Certification of Critical Raw Materials, coordinated by the French Geological Survey (BRGM).


ARATÓ, R., QUARLES, Jr. D., OBBÁGY, G., DALLOS, Z., ARATÓ, M., GOPON, P., MELCHER, F. (2025): Towards a chemical fingerprint of graphite by Laser-induced Breakdown Spectroscopy. Under review at Journal of Analytical Atomic Spectrometry