Zippeite and Johannite on Alunogen

Origin: Dove Creek (Dolores County, Colorado, USA)

Dove Creek lies within the Colorado Plateau uranium–vanadium district, where small mines were worked primarily in the mid-20th century. Oxidation in near-surface workings produced abundant secondary uranyl sulfates and related efflorescences on fractures and mine walls. From this locality, zippeite and johannite occur as vividly colored coatings on white alunogen crusts, creating striking contrast and illustrating late-stage, post-mining alteration.

Zippeite and Johannite on Alunogen

Zippeite and Johannite are hydrous uranyl sulfate minerals—strongly radioactive—while alunogen is a hydrous aluminum sulfate that forms a white, fibrous to powdery matrix. Zippeite typically forms canary-yellow to orange scaly crusts and films, and Johannite occurs as emerald-green coatings, tiny plates, or radiating sprays on the alunogen substrate. These species are soft and water-sensitive, may fluoresce, and characteristically develop as late supergene efflorescences in the oxidized zones of uranium deposits.