Schwertmannite
| Schwertmannite | |
|---|---|
 Schwertmannite | |
| General | |
| Category | Sulfate minerals |
| Formula (repeating unit) | Template:Iron8Template:Oxygen8(Template:Hydroxide)6(Template:Sulfate)·nH2O |
| Strunz classification | 7.DE.15 |
| Crystal system | Tetragonal Dipyramidal class |
| Space group | Tetragonal H-M symbol: (4/m) Space group: P4/m |
| Identification | |
| Color | brownish yellow |
| Luster | earthy |
| Streak | yellow |
| Diaphaneity | opaque |
| References | [1][2] |
Schwertmannite is an iron-oxyhydroxysulfate mineral with an ideal chemical formula of Template:Iron8Template:Oxygen8(Template:Hydroxide)6(Template:Sulfate)·nH2O or Fe3+16O16(OH,SO4)12-13·10-12H2O.[1] 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.[2]
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.[3]
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.[4] However, it is more commonly reported as an orange precipitate in streams and lakes affected by acid mine drainage.[5] Schwertmannite is also known to be central to iron-sulfur geochemistry in acid sulfate soils associated with coastal lowlands.[6]
References
- ^ a b Mindat
- ^ a b http://webmineral.com/data/Schwertmannite.shtml Webmineral
- ^ http://rruff.geo.arizona.edu/doclib/hom/schwertmannite.pdf Mineral Handbook
- ^ Bigham, JM, Carlson, L, Murad, E (1994) Schwertmannite, a new iron oxyhydroxysulfate from Pyhasalmi, Finland, and other localities. Mineral Mag 58, 641-664
- ^ 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.
- ^ 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