Remarkable hexagonal crystal with
well defined spiral showing a transition from rounded steps
near the center, to polygonalized nearer the crystal's edges.
John Rakovan collection and photo.
Geologic map of the sample locality, modified after Milner(1997).
Click on image for close up of the geology of the collecting site (star).
NkbAi is the Arises River member of the Karibib formation, Swakop Group
Namibian-aged (Neoproterozoic) metasediments.