Limonite — Limonite
Limonite Quatrostein, Wikimedia Commons, CC BY SA 3.0

Not a mineral · Iron oxides

Limonite

FeO(OH)·nH2O (mixture)

Limonite is a field term, not an IMA species, for earthy yellow-brown mixtures of goethite, lepidocrocite and other hydrated iron oxides. Limonite pseudomorphs after pyrite cubes (Spain, Utah) and 'limonite' box-work concretions are common collector items; the label should read 'goethite after pyrite' where the mineralogy is known. It is the stain on almost every weathered fossil.

FormulaFeO(OH)·nH2O (mixture)
IMA statusnot a mineral
Mohs hardness4–5.5
GroupIron oxides
Type localityNone

Elsewhere

Cite this article

Stratum Study. "Limonite" (Mineral). Stratum Study pack 2026.09, as of 2026-09-19. https://stratum.black/study/minerals/limonite. Accessed 2026-09-20.

@misc{stratum-limonite,
  title        = {Limonite},
  author       = {{Stratum Study}},
  howpublished = {\url{https://stratum.black/study/minerals/limonite}},
  year         = {2026},
  note         = {Mineral article, Stratum Study pack 2026.09, as of 2026-09-19; sources: stratum, wikidata, commons. Accessed 2026-09-20.}
}

Citations carry the pack version and the article's as-of date so they resolve to the same text later. The facts themselves belong to the sources listed below; cite those for the science.

Sources for this article: Stratum editorial (Stratum editorial);Wikidata (CC0);Wikimedia Commons (CC-BY-4.0). As of 2026-09-19; Study pack 2026.09. Data reproduced under the licences shown; text in Stratum's own words unless a section names its source.

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