Ferric hydroxide

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Goethite (ferric hydroxide)


A yellow to brown hydrated iron oxide material that occurs in nature as the minerals Goethite, lepidocrocite, and Limonite. Ferric hydroxide slowly loses water to form Ferric oxide or Rust. It is used as a Pigment, Catalyst, and rubber filler. Some commercial names for synthetically prepared yellow iron oxide compounds are Mars yellow, Mapico yellow, Ferrite, and Ferrox.

Synonyms and Related Terms

rust; ferric hydrate; iron hydroxide; iron hydrate; iron oxide, hydrated; ferric oxide, hydrated; ferric hydroxide oxide; ferrite yellow; yellow iron oxide; iron oxide yellow; goethite; limonite; jaune d'oxyde (Fr.); Oxidgelb (Deut.); Mars yellow; Mapico yellow; Ferrite; Ferrox;





Physical and Chemical Properties

Soluble in mineral acids. Insoluble in water, alcohols and ether.

Composition Fe(OH)3
CAS 20344-49-4
Mohs Hardness 5.0-5.5
Melting Point 156.5 C
Density 3.4-3.9 g/ml
Molecular Weight mol. wt. = 88.85

Resources and Citations

  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 4068