Cumengeite is an uncommon mineral that forms some of the most interesting crystal shapes of all minerals. Its most famous habit is as epitaxial overgrowths over Boleite, where a single specimen has an inner cubic core of Boleite, and outer protruding crystal faces of Cumengeite in triangular habit, forming a star-like formation.

Cumengeite has been found in several localities worldwide, however, its only significant source was the the Amelia Mine in Baja California, Mexico. To date, this is the only only locality that had produced this mineral in well-formed crystals of any significance.