tyuyamunite

Tyuyamunite is a uranium vanadate mineral with the chemical formula Ca(UO2)2(VO4)2·11H2O. It is a member of the carnotite group and is characterized by its bright yellow color. Tyuyamunite is a secondary mineral, meaning it forms through the alteration of other uranium-bearing minerals. It is typically found in oxidized zones of uranium deposits. The mineral was first described in 1942 from a discovery in the Tyuyamun deposit in the Fergana Valley, Uzbekistan, which gives it its name.

The crystal structure of tyuyamunite consists of layers of uranyl groups (UO2)2+ and vanadate groups (VO4)3-, with calcium ions and water molecules occupying the spaces between these layers. This layered structure contributes to its common platy or tabular crystal habit. Tyuyamunite is relatively soft, with a Mohs hardness of 2 to 2.5, and it has a specific gravity of around 3.1 to 3.4. It is insoluble in water but can be dissolved in acids.

Tyuyamunite is an important indicator mineral for uranium mineralization, as its presence suggests that uranium has been mobilized and redeposited. It is often found associated with other secondary uranium minerals such as carnotite, metatyuyamunite, and hewettite. While tyuyamunite itself is not a primary ore mineral, its occurrence can guide exploration efforts for more concentrated uranium deposits. Due to its radioactivity, appropriate handling precautions are advised when working with tyuyamunite.