Calcite, (w. Conichalcite)

Chemistry: CaCO3
Size: 69 mm
Owner: Mariusz Oleszczuk
Photographer: Mariusz Oleszczuk

A single colourless, translucent rhombohedral calcite crystal (c. 25 mm) rests on a multi-layered and somewhat cavernous crust of pink and white dolomite.  The dolomite is richly covered with spherules and sub-botryoidal crusts of dark-green conichalcite (XRD verified).  

The specimen was formerly in the collection of Franz Lammer (Austria), and was acquired by him in Tsumeb, during a safari to Namibia in 1979, from a vendor that he names as "Müller".