Iridescent Turgite

Turgite is a mixture of the two iron oxide minerals hematite and goethite. It is typically found in the botryoidal (globular) habit of the "parent" goethite. Turgite is often iridescent, meaning that it exhibits a rainbow of colors when viewed from different angles.

Originally described from Turjinskii Mine (Turginsk Mine) in Russia, turgite is generally considered a variety of two more common minerals – goethite and hematite. 

Turgite is not considered to be a valid mineral species by the International Mineralogical Association (IMA), as it does not have a unique chemical composition or crystal structure. However, it is still a popular mineral among collectors and enthusiasts, due to its iridescence and unusual appearance.

Iridescent Turgite. Incredible Iridescent Hematite stalactite from Graves Mountain, Georgia. Photo: Anatoly Bitny

Turgite is a mixture of the two minerals due to the alteration of goethite, typically found in the botryoidal (globular) habit of the “parent” goethite; however, because it is a mixture of two minerals, it is not considered a mineral in itself.

Goethite is a common iron mineral. It often forms by weathering of other iron-rich minerals, thus is a common component of soils. It may form excellent pseudomorphs after the original minerals particularly pyrite or marcasite. Goethite may also be precipitated by groundwater or in other sedimentary conditions, or form as a primary mineral in hydrothermal deposits. When present in sufficient quantities, it constitutes an important iron ore mineral.

It apparently only occurs under specific environmental conditions because the pieces I collected in Nevada and brought home to New Mexico lost their luster and turned to dull gray hematite.

Turgite is a relatively rare mineral, but it can be found in many parts of the world, including the United States, Canada, Europe, and Australia. Some of the most notable occurrences of turgite include the Ironwood Iron Formation in Michigan, the Labrador Trough in Canada, and the Erzgebirge Mountains in Germany.

 

Turgite coated in a cave