This is a fine thumbnail specimen from the original expeditions of Cumenge in the late 1800s, Ex. Sorbonne museum collections. It is a SHARP untwinned cumengeite, showing stereotypical classic form! Most cumengeite forms as twinned growth upon boleite crystals, and thus you have a starburst-shaped crystal habit. However, SOME FEW SPECIMENS from the original find, as is this one, show the untwinned habit. It is not quite pristine - there are a few small dings - but it has a good display face where they are hidden from view and "it is what it is," a holy grail of thumbnail and rare species collectors! I have had cumengeites, some larger and priced much higher, in the past. I have NOT had such an example, though, of this habit, before. There is an old label accompanying it which notes that it is a rare untwinned crystal (one of two known to him), from the collection of a Dr. FP D'Esopo. I do not think it is THAT rare, but it IS pretty uncommon. Then again, I now realize the WP on his label indicates that he got the piece from Dr. William Pinch, and Bill tends to be right about these kinds of things....CLICK ON LABEL FOR LINK TO THE COLLECTOR ARCHIVES AT THE MINERALOGICAL RECORD WEBSITE, AND MORE INFORMATION.