About the Mineral Goethite
Goethite which is correctly pronounced 'ger-tite' is a common iron mineral which takes on various forms and colours. It can be found all over the world and is present in abundance on Mars along with the mineral hematite.
Goethite often forms through the weathering of other iron-rich minerals and although usually black, it can occur in shades of yellow, brown or red depending on the impurities present. Fine crystallised specimens of goethite are rare but can be found in Cornwall (United Kingdom), France and Russia.
The mineral goethite can be translucent to opaque, it grades 5 to 5½ on Mohs scale of mineral hardness and was named in 1806 after the German poet Johann Wolfgang von Goethe who was a keen mineralogist. It's commonly found in rust and iron ore deposits and has been known since ancient times because it's the source of the yellowish brown colour in the pigment known as ochre.
The goethite mineral in the photo at the top of our page is on display in the Harvard Museum of Natural History, Cambridge, Massachusetts. Clicking the image redirects to the original full size photograph. Photo by Stone Mania ©