Fe5HO84H2O
Fe5HO84H2O is commonly written as Fe5HO8·4H2O and corresponds to ferrihydrite, a poorly crystalline iron oxyhydroxide mineral. Ferrihydrite is typically described as nanocrystalline or amorphous in structure, with iron in the Fe(III) state and a higher water content than more crystalline iron oxides. The mineral is notable for its high surface area and reactivity.
In terms of composition and structure, ferrihydrite consists of iron oxyhydroxide layers linked with hydroxide groups
Ferrihydrite forms through the hydrolysis and oxidation of soluble iron under neutral to slightly acidic conditions.
Physically, ferrihydrite appears as fine, reddish-brown to yellow-brown particles with a very high specific surface area.
See also: ferrihydrite, goethite, hematite, iron oxyhydroxides.