Characterization of Mn oxides in cemented streambed crusts from Pinal Creek, Arizona, U.S.A., and in hot-spring deposits from Yuno-Taki Falls, Hokkaido, Japan

FTIR Spectroscopic Study of Biogenic Mn-Oxide Formation byPseudomonas putidaGB-1

“…The data also indicate the presence of K, Ca, and Na in the biogenic solids, which is characteristic of naturally occurring birnessites. Electron diffraction patterns (Figure 2 inset b; ED spot size is 1 µm) indicate that the biogenic MnO x exhibits poor crystallinity relative to synthetic analogs (Drits et al 1997;Bilinski et al 2002), consistent with the X-ray diffraction studies of Villalobos et al (2003).…”

“…For example, Mandernack et al (1995) reported mixed phase minerals (hausmmannite, Mn 3 O 4 ; feiknechtite, β-MnOOH; manganite, γ -MnOOH, and Na-buserite) following Mn(II) oxidation by a marine Bacillus strain SG-1, whereas a nanocrystalline todorokite-like mineral was produced by Leptothrix discophora strain SP-6 (Kim et al 2003). The MnO x formed by P. putida strain MnB1 was found to be most similar to "acid" birnessite (Villalobos et al 2003), whereas Mn oxide crusts from Pinal Creek, AZ comprise a mixture of todorokite and birnessite or takanelite/ranciete, possibly deriving from a buserite precursor (Bilinski et al 2002;Gilbert 2003).…”

Formation of todorokite from vernadite in Ni-rich hemipelagic sediments

“…The structure-directing role of Mg, and its high concentration in seawater relative to Ca which reversely is more abundant in freshwater (Appelo and Postma, 1996;Andersen et al, 2005;Rezaei et al, 2005), explain why todorokite is widespread in marine deposits and seldom present in continental environments, such as soils (Chukhrov and Gorshkov, 1981;Dixon and Skinner, 1992;Vodyanitskii et al, 2004) or surface coatings and concretions formed in freshwater (Manceau et al, 2007a,b). Continental phyllomanganates generally are calcic (Taylor et al, 1964;Glover, 1977;Chukhrov et al, 1980aChukhrov et al, , 1985bMcKenzie, 1989;Bilinski et al, 2002;Manceau et al, 2007b), and experimental studies have shown that the conversion of Ca-exchanged birnessite to todorokite is incomplete and the products polyphasic (Golden et al, 1987).…”

Natural speciation of Ni, Zn, Ba, and As in ferromanganese coatings on quartz using X-ray fluorescence, absorption, and diffraction

“…The symmetry of the manganese layer can be hexagonal or orthogonal . Birnessites with hexagonal layer symmetry are the most common in nature (Glover, 1977; Bardossy and Brindley, 1978;Chukhrov et al, 1985;Duff et al, 1999;Bilinski et al, 2002;Manceau et al, 2003Manceau et al, , 2004Manceau et al, , 2005Buatier et al, 2004;Marcus et al, 2004b), and they have a structural charge arising predominantly from Mn vacancies and, occasionally from Mn 3+ for Mn 4+ substitutions, in the octahedral layer (Chukhrov et al, 1985;Silvester et al, 1997;Lanson et al, 2000;Ertl et al, 2005). Hexagonal birnessites tend to sorb hydrolyzable cations in their interlayer, and retain them at vacancy sites to compensate local charge.…”