Feroxyhyte structure

FeOOH (synthetic) and its poorly crystalline mineral form, feroxyhyte (5 -FeOOH), are reddish-brown, ferrimagnetic compounds. Their structures are based on hep anion arrays and differ in the ordering of the cations. Feroxyhyte was first described by Chukhrov et al. in 1976 and occurs (rarely) in various surface environments. 

Fig. 2.7 Structure of feroxyhyte. a) Hexagonal close packed anion layer with cations distributed over the interstices, b) Layers of edge-sharing octahedra. (a, b Stanjek, unpubl.)...

Fig. 1-1. Structural models of goethite, akaganeite, lepidocrocite, feroxyhyte, hematite and magnetite. Small, open circles indicate H atoms (from H. Stanjek, in Cornell and Schwertmann, 1996, with permission).

Feroxyhyte is a poorly ordered form of 5-FeOOH (and therefore called 5 -FeOOFI) discovered and introduced as a mineral by Chukhrov et al. in 1977. It is structurally related to the ferrimagnetic 5-FeOOH described by Glemser and Gwinner in 1939. 

Manganese oxides, which have different structural and surface properties, vary substantially in their ability to promote the precipitation and crystallization of Fe oxides and oxyhydroxides. The Mn(II) dissolved from Mn oxides in the presence of Fe(II) also influences the crystallization of oxidation products of Fe(II). The Fe oxides formed as influenced by Mn oxides and dissolved Mn(II) range from lepidocrocite, goethite, maghemite, dkaganeite, feroxyhyte, magnetite, honessite-like minerals, to noncrystalline Fe oxides. Therefore, Mn oxides deserve close attention in the genesis of Fe oxides. 

Manceau A, Decarreau A (1988) Extended X-ray absorption fine-structure study of cobalt-exchanged sepiolite Comment on a paper by Y. Fukushima and T. Okamoto. Clays Clay Minerals 36 382-383 Manceau A, Drits VA (1993) Local structure of ferrihydrite and feroxyhite [feroxyhyte] by EXAFS spectroscopy. Clay Minerals 28(2) 165-184... 

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