Schwertmannite

Schwertmannite

Schwertmannite

Sulfate mineral

Schwertmannite is an iron-oxyhydroxysulfate mineral with an ideal chemical formula of Fe8O8(OH)6(SO4) · n H2O or Fe3+
16O
16(OH,SO4)
12–13·10-12H
2O.[2] It is an opaque tetragonal mineral typically occurring as brownish yellow encrustations. It has a Mohs hardness of 2.5 - 3.5 and a specific gravity of 3.77 - 3.99.[3]

Quick Facts General, Category ...

It was first described for an occurrence in Finland in 1994 and named for Udo Schwertmann (born 1927) soil scientist, Technical University of Munich, Munich, Germany.[4]

Schwertmannite (with a distinct "pin cushion" morphology) commonly forms in iron-rich, acid sulfate waters in the pH-range of 2 - 4. The mineral was first recognised officially as a new mineral from a natural acid-sulfate spring occurrence at Pyhäsalmi, Finland.[5] However, it is more commonly reported as an orange precipitate in streams and lakes affected by acid mine drainage.[6] Schwertmannite is also known to be central to iron-sulfur geochemistry in acid sulfate soils associated with coastal lowlands.[7]

References

  1. [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. [2]
    Mindat
  3. [3]
    http://webmineral.com/data/Schwertmannite.sdoc Webmineral
  4. [4]
    http://rruff.geo.arizona.edu/doclib/hom/schwertmannite.pdf Mineral Handbook
  5. [5]
    Bigham, JM, Carlson, L, Murad, E (1994) Schwertmannite, a new iron oxyhydroxysulfate from Pyhasalmi, Finland, and other localities. Mineral Mag 58, 641-664
  6. [6]
    Bigham, JM, Schwertmann, U, Carlson, L, Murad, E (1996) Schwertmannite and the chemical modeling of iron in acid sulfate waters. Geochimica et Cosmochimica Acta 54, 2743-2758.
  7. [7]
    Burton, ED, Bush, RT, Sullivan, LA (2007) Reductive transformation of iron and sulfur in schwertmannite-rich accumulations associated with acidified coastal lowlands. Geochimica et Cosmochimica Acta 71, 4456-4473


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