Reduced manganese oxides

Compound or mineral Approximate formula Symmetry Space group Lattice constants Reference 

Compound or mineral Approximate formula Symmetry Space group a (pm) Lattice con.stants b (pm) c (pm) a (°) P (°) Y (°) Reference 

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Table 4. Crystallographic data for reduced manganese oxides and manganese oxide-hydroxides...

Copper in livers and muscles of Weddell seals was positively correlated with manganese (Szefer et al. 1994). In general, manganese and copper are positively correlated in tissues of marine vertebrates (Eisler 1984). Uptake of copper from copper-contaminated freshwater sediments by annelid worms is related to the amount of reducible manganese oxide in the sediments (Diks and Allen 1983). 

Chemetals A process for reducing manganese oxide to the metal by heating with methane and air. Developed by the Manganese Chemicals Corporation, Baltimore. 

The form of nickel in particles from different industries varies. The mineralogical composition, chemical content, and form of dusts from nine industries in Cracow, Poland, were examined (Rybicka 1989). The chemical form of a particle-associated heavy metal that was assessed by a five-step extraction scheme classified the metal as exchangeable, easily reducible (manganese oxides, partly amorphous iron oxyhydrates and carbonates), moderately reducible (amorphous and poorly crystallized iron oxyhydrates), organically bound or sulfidic, and residual. Dusts from power plants had a silicate characteristic with quartz and mullite predominant. Approximately 90% of the nickel from these... 

Model Ni/MnOx catalysts were prepared by 150-X nickel deposition onto an oxidized manganese disk under ultra-high vacuum. The surface composition of the catalyst wa-s followed as a function of time at 500 K in ultra-high vacuum. Rapid diffusion of reduced manganese oxide onto the nickel surface was observed. This oxide migration phenomenon was observed for a wide range of metal/... 

In natural systems microbiological oxidation may offer a faster pathway, particularly at pH < 8 and low concentrations (<5 jlM) of particulate oxides. Hastings and Emerson (17) showed that sporulated cultures of marine bacillus SG-1 at pH 7.5 accelerated the oxidation of Mn(II) by a factor of 104 with respect to the abiotic catalysis on a colloidal MnOz surface. A radiotracer study of microbial Mn oxidation in a marine fjord revealed half-lives as short as 2 days (18). Perhaps microorganisms can use the entire redox cycle of manganese. A study indicates that the vegetative cells of spores that mediate Mn(II) oxidation also reduce manganese oxides (19). 

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