Jarosite is seen here at the eastern end of St Oswald's Bay in Dorset, United Kingdom. This example has formed on the surface of pyritic sand and clay

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Jarosite is seen here at the eastern end of St Oswald's Bay in Dorset, United Kingdom. This example has formed on the surface of pyritic sand and clay containing plant remains (part of the Wealden Group). Oxidation of the iron sulphide pyrite can produce sulphuric acid and iron oxides. Reactions lead to the formation of the hydrated iron-bearing sulphate jarosite (with either sodium, potassium or ammonium). This yellow surface encrustation is often mistakenly referred to in old literature as sulphur. It is slowly soluble in water and is washed away to some extent by heavy rain but develops again in fairly dry weather.

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Photo credit: © ADRIAN BICKER/SCIENCE PHOTO LIBRARY / Alamy / Afripics
License: Licensed
Model Released: No

Keywords: chemical, chemistry, close-, compound, dorset, encrustation, formation, geography, geology, jarosite, kingdom, mineral, physical, pyritic, rock, rough, sand, textured, toughness, uk, uneven, united, yellow