gratonite

The earliest mention of gratonite at Tsumeb in the published literature appears to be by Bartelke (1976) who cited a 1973 TCL report (by Bruno Geier; unpublished) stating that gratonite was found in microscopic traces in ore from 30 Level. Bartelke’s description was repeated by Pinch and Wilson (1977) who added that gratonite occurs as "… dark metallic lead-gray microscopic masses …".

Lombaard et al. (1986) listed gratonite as an extremely rare mineral but without further comment. However, Hughes (1987) cautioned that the occurrence of gratonite is probable but requires verification.

Subsequent authors (for example Keller 1984; Gebhard 1999; Von Bezing et al. 2016) all included gratonite in their listings of Tsumeb minerals, apparently based only on the note by Bartelke (1976) and without further substantiation.

The occurrence of gratonite at Tsumeb is considered questionable pending reliable confirmation.

Undetermined