Goethite Common Iron Mineral | Facts and Photos

What is Goethite?

Goethite, correctly pronounced 'ger-tite', is a naturally occurring iron oxide mineral that takes on various forms and colours. It forms through the oxidation of iron in the presence of water and oxygen.

It can be found all over the world and is abundant on Mars.

Goethite, named after the German poet, playwright and keen mineralogist Johann Wolfgang von Goethe, was first described in 1806.

It often forms through the weathering of other iron-rich minerals such as hematite and magnetite. Although usually black, it can occur in shades of yellow, brown or red, depending on the impurities present.

Fine crystallised goethite is rare but can be found in Cornwall (United Kingdom), France and Russia. 

Goethite, which can be translucent to opaque, is commonly found in rust and iron ore deposits. On the Mohs scale of hardness, it grades 5 to 5.5.

It can be found as needle-like crystals but more commonly occurs in masses. In mineralogy, 'massive' crystal habit refers to a type of crystal growth where the mineral forms as a solid mass without any external crystal faces.

Goethite is known to have been used since ancient times because it's the source of the yellowish-brown colour in the pigment known as ochre.

Scientists study goethite to better understand Earth's weathering processes. It also helps to identify the conditions under which iron minerals form and evolve. Hematite, magnetite and goethite are the most abundant iron oxides in nature.

Article Pictures

The goethite mineral in the photo at the top of our article is on display in the Harvard Museum of Natural History, Cambridge, Massachusetts. The image is clickable and redirects to the original photo.

Pop-up photos: Hematite - Courtesy of Ron Wolf. Magnetite - Courtesy of Stan Celestian.