Tyuyamunite in Petrified Wood - Monument No. 2 Mine, Monument No. 2 channel, Yazzie Mesa, Cane Valley Mining District, Apache County, Arizona, USA

Ca(UO₂)₂(VO₄)₂ · 5-8H₂O

Tyuyamunite is a bright yellow-green, uranium-vanadium mineral that often occurs in oxidized zones of uranium deposits. In the Monument #2 mine, located on the Navajo Nation in northeastern Arizona, tyuyamunite is famously found encrusting and impregnating petrified wood. This mineral forms in association with fossilized plant material due to the wood's natural ability to act as a chemical trap, concentrating uranium and vanadium from groundwater. Over time, these elements react to form tyuyamunite, which precipitates within the cavities and along the grain structure of the wood, preserving its texture in vivid hues.

The striking appearance of tyuyamunite in petrified wood makes it a prized specimen among collectors and mineral enthusiasts. The contrast between the vibrant, radioactive mineral and the muted, fossilized wood highlights the interplay between organic processes and inorganic mineralization. The Monument #2 mine, once a significant producer of uranium during the mid-20th century, showcases the unique geological conditions that foster the formation of such mineralogical treasures. Specimens from this locality not only hold aesthetic appeal but also serve as fascinating records of the region’s geological and environmental history.

Approx. specimen size: 80mm x 60mm x 40mm

Approx. activity on an SE International Ranger EXP: 103400 cpm