Habit: Emerald green, grass green or apple green. Thin to thick tabular crystals, typically in subparallel aggregates, foliated or micaceous. Vitreous, subadamantine or waxy luster, becoming dull on dehydration; transparent to translucent. Pale green streak.
Environment: An uncommon secondary mineral formed in the oxidized zones of some uranium-rich copper deposits; associated with metatorbernite, autunite and uraninite.
Etymology: Named after Torbern Olof Bergmann (1735-84), a chemist and mineralogist at Uppsala University in Sweden.