Mottramite, Calcite – Tsumeb, Otavi, Namibia
 Ex Anton Berger
 Former Umrath
 Former Peter Pichler Collection
 A gigantic and historic showcase specimen of the rare mineral mottramite from the extinct Tsumeb Mine. The black, shimmering mottramites are beautifully crystallized and grow in a very deep vein.
 The step was bought from Anton Berger by the Kranz company in Bonn in 1967 and comes with a typewritten label by Anton Berger with handwritten additions and a label from the Karl Umrath collection, Graz.