Feroxyhyte

Feroxyhyte is an oxide/hydroxide of iron, δ-Fe3+O(OH). Feroxyhyte crystallizes in the hexagonal system. It forms as brown rounded to concretionary masses. Feroxyhyte is opaque, magnetic, has a yellow streak, and has a relative density of 4.2.[3]

Feroxyhyte
General
CategoryOxide mineral
Formula
(repeating unit)		δ-Fe3+O(OH)
IMA symbolFox[1]
Strunz classification4.FE.40
Dana classification06.01.04.04
Crystal systemHexagonal
Unknown space group
Unit cella = 2.95, c = 4.56 [Å]; Z = 1
Identification
Formula mass88.85 g/mol
ColorBrown, yellow-brown
Crystal habitConcretionary, massive, nodular
StreakYellow
DiaphaneityOpaque
Specific gravity4.31
Density4.2
Optical propertiesUniaxial
References[2][3][4]

It occurs in manganese-iron nodules on the Atlantic and Pacific Ocean floors. It is also found in the Baltic, White, and Kara Seas.[5] Forms under high pressure conditions and reverts to goethite on exposure to surface conditions.[3] It also occurs as cement and coatings on clasts in poorly drained soils and sediments, formed by the rapid oxidation of iron(II) oxide compounds.[5]

It was first described in 1976 for an occurrence in soils at its type locality: Kolomyya, Ivano-Frankivsk Oblast, Ukraine.[2][5]

References
  1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. "Feorxyhyte mineral information and data". Mindat.org. Retrieved 2011-10-24.
  3. "Feroxyhyte Mineral Data". Webmineral.com. Retrieved 2011-10-24.
  4. "Information card - FEROXYHYTE". Mineral Crystal Structure Database. Retrieved 2011-10-24.
  5. Handbook of Mineralogy


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