Chemistry: CaCO3
Size: 90 mm
Owner: Mariusz Oleszczuk
Photographer: Mariusz Oleszczuk

An undulating, sky-blue crust of aragonite flowstone coloured, presumably, by included copper salts.  Most aragonite of this habit at Tsumeb is of post-mining origin.  

What is unusual about this specimen, is that the aragonite has formed over a crystal of cerussite that appears to have been richly encrusted (or perhaps partly pseudomorphed) by mimetite (see Photograph 2).