Identification of Beryl Inclusions in Muscovite Using DE-XRT with Polynomial Calibration

Identifying beryl within muscovite host rocks is a challenging task for traditional X-ray transmission (XRT) separation due to the proximity of their effective atomic numbers (Zeff) and densities. In this paper, an improved dual-energy X-ray transmission (DE-XRT) method using second-order polynomial calibration is proposed to compensate for the beam hardening effect in massive samples. To verify the accuracy of the method, natural beryl and muscovite intergrowths were investigated on an experimental DE-XRT setup (160 kV), and the results were compared with computed tomography (CT) data. The results confirm that the polynomial model reliably identifies both exposed and hidden (internal) beryl inclusions. It was established that at a sample thickness of approximately 20–30 mm, the system confidently detects inclusions constituting more than 15% of the total thickness; this threshold serves as a preliminary quantitative estimate given the finite sample set. With an increase in thickness beyond 40 mm, the detection threshold rises due to significant absorption of the low-energy spectrum component, which leads to a loss of dual-energy contrast and a critical reduction in the signal-to-noise ratio. The proposed approach creates a basis for effective beryl pre-concentration, ensuring the preservation of large crystals from mechanical damage during crushing.