An EPMA and SEM study of the Mn-oxide mineralization of Kato Nevrokopi, Macedonia, northern Greece: Controls on formation of the Mn ⁴⁺ oxides

Abstract

EPMA and SEM studies of tunnel-structured todorokite and nsutite and layerstructured chalcophanite and birnessite from the Kato Nevrokopi battery grade Mnmineralization were performed. The chemistry of todorokite, formed at hypogene and supergene environments in an increasing order of weathering, reflects different pH and oxidation conditions. The data also point to a clear dependence of the development of late stage hypogene and early supergene Mna+-oxide paragenesis on the host rock and protore composition and the mobilities of base metals (mainly Zn), alkalis and alkaline earths (mainly Ca).The chemistry and development of (large cation-bearing) nsutite as in situ oxidations and

Precipitation of Mn Oxides in Quaternary Microbially Induced Sedimentary Structures (MISS), Cape Vani Paleo-Hydrothermal Vent Field, Milos, Greece

“…SEM-backscatter electron (BSE) imaging reveals morphological domination by elongated fibers (>5.0 µm) of crystalline todorokite ( Figure S4A), and FEG-SEM imaging shows nanocrystalline todorokite in the form of fibrous needles (<0.4 µm) ( Figure S4B). SEM-energy-dispersive X-ray spectroscopy (EDX) analyses of the fibres (Table S2) are consistent with todorokite [80,81], composed of 76-82 wt.% Mn(III/IV)O 2 . FEG-SEM EDS elemental maps of todorokite nanoplatelets are shown in Figure S5.…”

Manganese Valence in Oxides Formed from in Situ Chemical Oxidation of TCE by KMnO4

“…Manganese oxides are well-known for the range of mineral structures they exhibit − . Given the redox-active nature of Mn and the variability in mineral structures, it is possible to form oxides containing the three common valence states of Mn: Mn II , Mn III , and Mn IV − .…”

Electrochemical Behavior of Natural Manganese Oxides: Transforming Mining Waste into Energy Storage Materials

“…The samples collected represent ore from waste piles which are disposed of adjacent to the closed mine sites of Mavro Xylo and "25th Km", Kato Nevrokopi, Drama, Greece. The ore paragenesis in these sites mainly consists of pyrolusite, nsutite (MnO 2 ), and todorokite [Ca,K,Na,Mg,Ba,Mn)(Mn,Mg,Al) 6 O 12 *3H 2 O] at various abundances [23,24]. The mineralogy of the studied samples is verified prior to the experiments by XRD analysis showing that the MLX3 is mostly comprised of nsutite and sample MLX1 is a mixture of nsutite and todorokite with minor matrix calcite.…”