Goethite - Wikipedia
/ ˈ ɡ ɜːr t aɪ t / is a mineral of the diaspore group, consisting of ironIII oxide-hydroxide, specifically the "α" polymorph.It is found in soil and other low-temperature environments such as sediment. has been well known since ancient times for its use as a pigment brown ochre.Evidence has been found of its use in paint pigment samples taken from the caves of ...