Locality: The mine dump of the Lichtenberg open-pit at the southwest margin of Ronneburg, Thuringia, Germany.
Occurrence: In a uranium deposit in slates and limestones. Associated minerals are: hummerite, gypsum, epsomite, picromerite, hematite and an unidentified K–Mg–Mn vanadate. Sincosite, simplotite and straczekite were found a few meters away. More than 230 species are known from the Ronneburg deposit.
General appearance: Crystals of equant, flattened or short prismatic habit (up to 0.5 mm).
Physical, chemical and crystallographic properties: Luster: adamantine. Diaphaneity: translucent. Color: reddish brown. Streak: brownish orange. Luminescence: nonfluorescent. Hardness:...