New data on the geochemical and mineralogical features of the main manganese- and iron-bearing ore occurrences in the Central Srednogorie Zone, Bulgaria

The main goal of the present study is characterization mineralogical and geochemical features polymetallic (Mn- Fe-bearing) nodules, lens- layer-like bodies from different localities in central part Late Cretaceous Srednogorie metallogenic zone, Bulgaria. research based on field studies, sampling optical microscopy, followed by a combination analytical techniques: XRD, SEM-EDS, ICP-OES LA-ICP-MS methods. They define pyrolusite as ore mineral studied occurrences, while manganite, todorokite, bixbyite, sarkinite, hematite hauerite are rarer. most common gangue minerals quartz, calcite zeolites. Based MnO/SiO2 ratio, established divided into two groups: manganese (i) silica-manganese (ii) phases, respectively. Their trace element composition dominated high content V, Zn, Mo, W, Co, Ni, Cu, As, Tl Sr, whereas some them belong to group critical raw materials for high-tech products. measured values Y rare earth elements oxides hydroxides low compared their concentrations modern nodules Pacific Ocean. Chondrite-normalized patterns indicated weak LREE enrichment with respect MREEs HREEs, which slightly depleted. Common strong negative Ce anomaly, accompanied various Sm Eu anomalies, also observed. close proximity volcanic rocks Mn- Fe-bearing mineralization structural textural suggest hydrothermal origin Mn-Fe occurrences Panagyurishte area.