Goethite is a mineral of the diaspore group, consisting of iron(III) oxide-hydroxide, specifically the α-polymorph. It is found in soil and other low-temperature environments such as sediment. Goethite has been well known since ancient times for its use as a pigment. Evidence has been found of its use in paint pigment samples taken from the caves of Lascaux in France. It was first described in 1806 based on samples found in the Hollertszug Mine in Herdorf, Germany. The mineral was named after the German polymath and poet Johann Wolfgang von Goethe (1749–1832).
Goethite
Unusual specimen of goethite replacing a gypsum stalactite; the center is hollow. From Santa Eulalia, Chihuahua, Mexico.
A microscopic picture of Goethite (name misspelled on picture)
Iridescent goethite, Filón Sur Mine, Tharsis, Huelva, Spain
Ochre, iron ochre, or ocher in American English, is a natural clay earth pigment, a mixture of ferric oxide and varying amounts of clay and sand. It ranges in colour from yellow to deep orange or brown. It is also the name of the colours produced by this pigment, especially a light brownish-yellow. A variant of ochre containing a large amount of hematite, or dehydrated iron oxide, has a reddish tint known as red ochre.
Ochre pigment
Yellow ochre (Goldochre) pigment
Limonite, a mineraloid containing iron hydroxide, is the main ingredient of all the ochre pigments.
Hematite is a more reddish variety of iron oxide, and is the main ingredient of red ochre.