Locality: The Clara mine, central Black Forest, Germany.
Occurrence: Associated minerals are: barite, quartz, goethite and cornwallite.
General appearance: Acicular crystals up to 0.5 mm long and almost 0.01 mm thick; commonly in radiating aggregates.
Physical, chemical and crystallographic properties: Luster: vitreous, in part silky. Diaphaneity: transparent to translucent. Color: light green to yellowish green. Streak: greenish to pale yellow. Luminescence: nonfluorescent. Hardness: about 3. Tenacity: not given, probably brittle. Cleavage: not observed. Fracture: not given. Density: 3.70 g/cm3 (meas.), 3.67 g/cm3 (calc.). Crystallography...