Zeunerite - Grand View Mine, Grand Canyon, Arizona, USA

Cu(UO₂)₂(AsO₄)₂ · 12H₂O

Zeunerite from the Grand View Mine in the Grand Canyon, Arizona, is a striking secondary uranium mineral known for its vibrant green color and tabular crystal habit. It belongs to the torbernite group and has the chemical formula $Cu(UO_2)_2(AsO_4)_2 \cdot 8-12H_2O$, indicating it is a hydrated copper uranyl arsenate. This mineral forms as an alteration product of primary uranium minerals in oxidizing conditions, often appearing as fine, crystalline aggregates or coatings on the surfaces of host rocks.

The Grand View Mine, located within the iconic Grand Canyon, is a historic site known for its uranium and vanadium deposits. Zeunerite occurs there as a secondary mineral within brecciated and oxidized zones of the host rock, often associated with malachite, azurite, and other secondary copper minerals. The mine's unique geological setting, including the interaction of uranium-rich fluids with arsenic-bearing minerals, creates ideal conditions for the crystallization of zeunerite.

Zeunerite specimens from the Grand View Mine are prized for their vivid green coloration, which results from the copper content in the mineral. The tabular crystals often form in radial or rosette-like patterns, enhancing their aesthetic appeal. These specimens are not only valued by collectors for their beauty but also by researchers interested in the secondary mineralization processes of uranium-bearing deposits.

From a scientific perspective, zeunerite provides valuable insights into the geochemical conditions of uranium mobility and secondary mineral formation. The mineral's stability under oxidizing conditions and its ability to incorporate copper and arsenic into its structure make it a key indicator of the environmental processes at play in uranium deposits. Its formation reflects the unique interplay of hydrothermal fluids, host rock composition, and oxidation states present in the Grand Canyon region.

Approx. specimen size: 40mm x 35mm x 30mm

Approx. specimen activity on an SE International Ranger EXP: 4100 cpm