This is a really old and potentially quite important specimen from the Wittichen area in Black Forest, Baden-Württemberg, Germany. It features a 7 mm wide grey metallic cubic crystal of Cobaltite embedded in Calcite. Somewhat remarkably Mindat.org does not list Cobaltite as occurring at Wittichen, despite it being a cobalt-mining region. Ordinarily, this might raise questions regarding accurate provenancing of the specimen, but for the two accompanying old handwritten labels. Both record the locality and refer to the species as Kobaltglanz, the old German name for Cobaltite. One of the labels (dated 1909) records it as from the collection of Senator Friedrich Jakob Kessler (1805-1889). The 1909 date appears to be when Kessler's collection was catalogued in the Senckenberg Museum but it is unclear if the other label is Kessler's own label or a museum label too. Most recently the specimen was part of the superb collection assembled by brothers Martin and Michael Günther (1951-2007 & 1956-2021).