Ore grade analysis is the laboratory and field-based process of determining the concentration of valuable elements or minerals within an ore sample, providing the quantitative basis for grade control, reserve estimation, and metallurgical planning. Techniques vary by commodity due to differing chemical and physical properties of the target mineral. Gold grade analysis traditionally relies on fire assay, in which a sample is fused with fluxes and lead to collect gold into a bead that is then weighed, though instrumental techniques such as atomic absorption spectroscopy and inductively coupled plasma mass spectrometry are also widely used for faster turnaround. Iron ore and bauxite grade analysis commonly uses X-ray fluorescence (XRF) spectrometry, which rapidly measures elemental composition including Fe, Al2O3, SiO2, and other oxides relevant to processing decisions. Diamond grade analysis is fundamentally different because diamonds must be physically recovered and counted rather than chemically measured; this typically involves processing bulk samples through dense media separation and X-ray transparency or luminescence sorting machines to recover and then individually weigh and grade each stone, a labor- and capital-intensive process compared to elemental assay methods used for the other three commodities.
