The Effect of Mn Substitution on Natural Sphalerites by Means of Raman Spectroscopy: A Case Study of the Sacaramb Au-Ag-Te Ore Deposit, Apuseni Mountains, Romania

Natural samples of sphalerites containing Mn in the range 0 <= x <= 0.25 apfu from the Sacaramb 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 (Zn0.87Fe0.16)(Sigma=1.03)S-0.97 to manganoferroan (Zn0.77Mn0.14Fe0.06)(Sigma)S-=0.97(1.03), as well as mangan-rich (Zn0.8Mn0.25)(Sigma)S-=1.05(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 Sacaramb 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).