TYUYAMUNITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Uranyl vanadates
    Crystal system : Orthorhombic
    Chemistry : Ca(UO2)2(VO4)2 5-8H2O
    Rarity : Uncommon

Tyuyamunite is a secondary uranium mineral that is quite widespread in the oxidation zone of deposits of this metal where it is associated in particular with carnotite, its calcium analogue, and with metatyuyamunite by dehydration. Its name comes from its discovery locality : Tyuya Muyun (Kyrgyzstan). Tyuyamunite constitutes impregnations, masses or powdery coatings, sometimes small waxy yellow to lemon yellow lamellar crystals, elongated along [100] and flattened on {001}, with frequently curved faces. Crystalline aggregates with radiate and fan-shaped textures are also known. It is a locally important ore of uranium and vanadium.

Main photo : Tyuyamunite from Marie Mine, Montana, USA © Christophe Boutry

Tyuyamunite from Tyuya-Muyun, Kyrgyzstan © Uwe Haubenreisser
Tyuyamunite from Qinglong Mine, Guizhou, China © Elise Chaigneau & Eric Penet
Tyuyamunite from Clara Mine, Germany © Michael Förch
Tyuyamunite from Ridenour Mine, Arizona, USA © Tony Peterson

Tyuyamunite in the World

Tyuyamunite is common in most carnotite uranium deposits, particularly in the United States (Colorado, New Mexico, Arizona). The Laguna deposit near Grants (New Mexico) has provided good crystallized specimens. However, the most beautiful crystals come from the type locality of Tyuya-Muyun in Kyrgyzstan, where this mineral was sufficiently abundant to constitute a true uranium ore.

Tyuyamunite in France

In France, tyuyamunite is reported at Rabejac (Hérault), Autun and Charolles (Saône-et-Loire) and St-Priest-la-Prugne (Loire).

Twinning

No twinning known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 1.5 to 2
Density : 3.57 to 4.35
Fracture : Micaceous
Streak : Yellow

TP : Translucent to opaque
RI : 1.675 to 1.895
Birefringence : 0.210
Optical character : Biaxial -
Pleochroism : Weak
Fluorescence : Yellow

Solubility : Acids

Magnetism : NoneRadioactivity : Strong