Unkown Tsumeb material (under study)

Item Description

This is a typical example of the weird plastic-like substance from Tsumeb known as GS1 or GS2 for many years. It is lightweight, pretty lime-green massive material with good luster and conchoidal fracture, similar to chert. It is nicely translucent on the edges. From a small recently uncovered stash of old material. There is debate about what it is. Koritnigite is an ultra rare zinc arsenate, not described until 1979 from the famous and now-closed Tsumeb Mine. The (previously posted) ID of Koritnigite has been tossed around and told me by respected collectors, in part citing an analysis done by Tony Nikischer at Excalibur (but not on this sample). I should say here there is doubt to the ID and one should buy this as an "unknown" and interesting Tsumeb thing in need of further study. It is amorphous and should not yield crystal data, as I understand it.