Sphalerite Composition in Low- and Intermediate-Sulfidation Epithermal Ore Bodies from the Roșia Montană Au-Ag Ore Deposit, Apuseni Mountains, Romania

Abstract

We evaluated the significance of the iron and manganese content in sphalerite as a tool for distinguishing between low-sulfidation and intermediate-sulfidation epithermal deposits on the basis of new and previously published electron probe microanalyses data on the Roșia Montană epithermal ore deposit and available microchemical data from the Neogene epithermal ore deposits located in the Apuseni Mountains and Baia Mare region, Romania. Two compositional trends of the Fe vs. Mn content in sphalerite were delineated, a Fe-dominant and a Mn-dominant, which are poor in Mn and Fe, respectively. The overlapping compositional range of Fe and Mn in sphalerite in low-sulfidation and intermediate-sulfidation ores suggests that these microchemical parameters are not a reliable tool for distinguishing these epithermal mineralization styles.

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

“…In contrast, wurtzite (a high-temperature polymorph of sphalerite) can absorb ~50 mol.% almost without temperature dependence [38]. To the best of our knowledge, this is the highest Mn content (up to 14.1 wt.%) in sphalerite reported within the Golden Quadrilateral ore deposits (up to 6.01 wt.% at Roşia Montană [39]) and the Baia Mare mining district (0.86 wt.% at Şuior [40]). Previously, Cook et al [1] reported up to 6.75 wt.% in Săcărâmb hydrothermal ore deposit.…”

“…1. Natural sphalerites of 𝑍𝑛 1−𝑥 𝑀 𝑥 𝑆 (M = Mn, Fe), where x is in the range of 0.0 Mare area [40], and Roşia Montană [39].…”

“…It is suggested that in nature, the presence of Mn-rich sphalerite is strongly related to the cogenetic Mn minerals associated with ore deposits. Mn-rich sphalerites have been discovered in two types of hydrothermal deposits: (i) Mn skarn deposits, in which the sphalerites are associated with Mn-Fe spinels, Mn carbonates, and alabandite [42,47]; and (ii) in epithermal Au-Ag deposits in association with alabandite and Mn carbonates [20,39,41]. The presence of Mn carbonates (i.e., rhodochrosite and manganocalcite) is a common diagnostic feature to discern IS from LS epithermal deposits [48,49].…”

“…Minerals 2022, 12, x FOR PEER REVIEW discovered in two types of hydrothermal deposits: (i) Mn skarn deposits, in wh sphalerites are associated with Mn-Fe spinels, Mn carbonates, and alabandite [42,4 (ii) in epithermal Au-Ag deposits in association with alabandite and Mn carb [20,39,41]. The presence of Mn carbonates (i.e., rhodochrosite and manganocalc common diagnostic feature to discern IS from LS epithermal deposits [48,49].…”

“…A sulfide resurgence induced the second formation proc carbonate-rich and low-sulfur fluid that dissolved the main Mn ore and reprecip more chemically complex sphalerite in association with pyrite, galena Ag-Cu sul tellurides, and alabandite (Figure 8, type 3). Mare area [40], and Roşia Montană [39].…”