page_title: Iron(II) hydroxide
section_title: Natural occurrence
hierarchical_section_title: Iron(II) hydroxide / Natural occurrence
caption_attribution_description: English: Groundwater pollution on a limestone building. Building located in Perth, Western Australia
context_page_description: Iron(II) hydroxide or ferrous hydroxide is an inorganic compound with the formula Fe(OH)₂. It is produced when iron(II) salts, from a compound such as iron(II) sulfate, are treated with hydroxide ions. Iron(II) hydroxide is a white solid, but even traces of oxygen impart a greenish tinge. The air-oxidised solid is sometimes known as "green rust".
context_section_description: Iron dissolved in groundwater is in the reduced iron II form. If this groundwater comes in contact with oxygen at the surface, e.g. in natural springs, iron II is oxidised to iron III and forms insoluble hydroxides in water.
caption: Iron III hydroxide staining caused by oxidation of dissolved iron II and precipitation, Perth, Western Australia.
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