Natural samples of sphalerites containing Mn in the range 0 ≤ x ≤ 0.25 apfu from the Săcărâmb Au–Ag–Te ore deposit, found in the Apuseni Mountains, Romania, were investigated using Raman spectroscopy to determine its capability to provide estimates of Mn content. Raman data for the natural Mn-rich sphalerite have not been published so far, with the largest concentration of Mn in sphalerites being from Romanian territory (i.e., 14.1 wt.%). The results are in good agreement with SEM-EDS data. In this study, three genetic types of sphalerites were identified: from ferroan ${\left(Z{n}_{0.87}F{e}_{0.16}\right)}_{\sum =1.03}{S}_{0.97}$ to manganoferroan ${\left(Z{n}_{0.77}M{n}_{0.14}F{e}_{0.06}\right)}_{\sum =0.97}{S}_{1.03}$, as well as mangan-rich ${\left(Z{n}_{0.8}M{n}_{0.25}\right)}_{\sum =1.05}{S}_{0.95}$ compositions. Sphalerites with a high content of Mn (up to 14.1 wt.%) were strongly connected to the presence of alabandite in the mineralized assemblages. The formation of several types of sphalerites in the Săcărâmb Au–Ag–Te ore deposit was caused by the succession of different types of hydrothermal fluids and the interaction between the fluids and the host materials (host rocks and earlier mineralized stages).

Valorising mining waste is critical for sustainable resource management and reduced reliance on primary raw materials. Waste dumps from large-scale porphyry systems are potential secondary sources of critical raw materials (CRMs) as listed in Regulation (EU) 2024/1252. This study investigates mineralogical and microchemical heterogeneity in wastes from the Roșia Poieni porphyry copper district, Romania, testing the hypothesis that this heterogeneity governs both their secondary-resource potential and their environmental behaviour. Samples from the Geamăna and Halda Veche waste dumps were characterised by powder X-ray diffraction (PXRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), and Raman spectroscopy. PXRD of five selected samples revealed marked inter-sample variability: chalcopyrite ranged from 12.88% to 13.48%, bornite and rutile reached 7.84% and 7.60%, and cuprite reached 15.78%. SEM-EDS confirmed Cu-rich bornite (55.25 wt.% Cu), while Raman spectroscopy identified melanterite alongside calcite and dolomite. The identification of pyrite, melanterite, and carbonate minerals suggests potential acid-generating and acid-neutralising processes, although validation by leaching tests and acid-base accounting is required. These findings establish a mineralogical basis for evaluating targeted recovery of critical and strategic raw materials alongside environmentally responsible mine waste management within a circular-resource framework; representative bulk geochemical analyses and recovery tests are still required to establish recoverable resources.