Out of both the Carl Bosch and Smithsonian collections, this is a substantial and outstanding specimen of Pseudomalachite. The rich green color, and very good luster (particular where you see the radial pattern of crystal growth and the terminations) highlight what is already an amazing example of the species for sheer size. This relatively uncommon hydrated copper phosphate, found in the oxidized of copper deposits, is normally seen as only small crystal groups or small botryoids. Older, very rich, and colorful, this is excellent example from one of the historic mines in Germany. Bosch was known for collecting quality, big or small in any size. The provenance is very important: http://minrec.org/labels.asp?colid=205
. He was awarded the Nobel Prize in Chemistry in 1931 for his work on high-pressure ammonia (fertilizer) synthesis!