Goethite Iron Mineral Facts and Photos
What is Goethite?
Goethite which is correctly pronounced "ger-tite" is a naturally occurring iron oxide mineral which takes on various forms and colours. It can be found all over the world and is present in abundance on Mars.
Goethite is named after the German poet, playwright and keen mineralogist Johann Wolfgang von Goethe. It was first described in 1806 and is widely distributed throughout the world.
The mineral goethite 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.
Goethite has a hardness of 5 to 5.5 on Mohs scale. It can be found as needle-like crystals but commonly occurs in masses. Crystals that occur in this crystal habit grow as a tightly intergrown mass. Individual crystals exhibit no external visible shape or form.
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 in order to gain a better understanding of Earth's weathering processes. It also helps them identify the conditions under which iron minerals form and evolve. Hematite, magnetite and goethite are the most abundant iron oxides in nature.
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 non-compressed photo.