Uranocircite is a barium uranyl phosphate hydrate and a member of the Autunite Group. It forms thin tetragonal, translucent, greenish yellow to yellow, tabular crystals in clusters and fan-like sub-radial aggregates with a pearly luster, especially on cleavage surfaces. It fluoresces a beautiful yellow-green with UV light. Uranocircite typically occurs as a secondary mineral in the oxidized zone of uranium deposits; in granite pegmatites; and in low-temperature hydrothermal veins.Uranocircite occurs at the Bergen U deposit, Zobes-Bergen District, Vogtland, Saxony, Germany, the type locality, Other notable localities include: Sao Pedro mine, Saucui, Teofilo Ontoni, Minas Gerais, Brazil (as exceptional crystals); Wharf mine, Bald Mountain district, Lawrence Co., and Slim Buttes, Harding Co., South Dakota, USA; Dametice, near Horazdovice, Bohemia, Czech Republic; Wolsendorf, Bavaria, Germany; El Cabril, Fuente-Ovejuna, Cordoba Province, Spain; and many occurrences in the sandstone-hosted uranium deposits of Arizona, New Mexico, Colorado, and Utah, USA. Explore and learn about uranocircite fine mineral specimens online at www.iRocks.com.