Rauvite, Carnotite, Tyuyamunite & Metahewiettite - Uravan Mineral Belt, Western Colorado, USA

CaV₆O₁₆ · 3H₂O   K₂(UO₂)₂(VO₄)₂ · 3H₂O   Ca(UO₂)₂(V₁₀O₂₈) · 16H₂O Ca(UO2)2V2O8·(5-8)H2O

The Uravan Mineral Belt in western Colorado is a renowned locality for its rich assemblage of uranium-vanadium minerals, including rauvite, carnotite, tyuyamunite, and metahewettite. Rauvite, a rare calcium uranium vanadate, often appears as dark brown to black crusts or fine-grained aggregates on oxidized sandstone. Its formation occurs in highly oxidizing environments, reflecting the unique geochemical conditions of the Colorado Plateau. Carnotite and tyuyamunite, the bright yellow and greenish-yellow potassium and calcium uranium vanadates, respectively, are frequently found as vivid crusts or delicate coatings on rock surfaces. Together, these minerals create a striking visual contrast and serve as markers of secondary uranium enrichment, driven by the interaction of groundwater and vanadium-bearing sediments.

Adding to this mineralogical diversity is metahewettite, a reddish-brown to black hydrous calcium uranium vanadate that often forms as a secondary alteration product. Its presence alongside rauvite, carnotite, and tyuyamunite highlights the district's dynamic geological history, characterized by oxidation-reduction cycles that concentrated uranium and vanadium in sandstone-hosted deposits. Specimens from the Uravan Mineral Belt are prized for their aesthetic appeal and scientific importance, providing insights into the processes that formed one of the most significant uranium-vanadium mining regions in the United States. These minerals not only reflect the legacy of uranium mining in the mid-20th century but also offer a glimpse into the intricate interplay of mineralogy and geochemistry in sedimentary environments.

Approx. activity: 3500 cpm

Approx. size: 20mm x 20mm x 5mm