Goethite is a hydrated iron oxide, Fe3+O(OH). Its hardness ranges from 5.0 to 5.5, and its specific gravity varies from 3.3 to 4.3. It forms needle-like crystals, and is not generally considered very interesting as a mineral specimen; its main use is as an iron ore. Colour brown.

Related to the mineral Feroxyhyte FeO(OH).

Goethite was discovered by the German writer Johann Wolfgang von Goethe who was also interested in science.

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