These include arsentsumebite, tsumebite, corkite, fornacite, duftite, caledonite, kettnerite, linarite, leadhillite, brochantite, mimetite, pyromorphite, vanadinite and wulfenite.
At the Reward mine green botryoids (0.5 mm) of calcian duftite were found associated with uncommon elongate white mimetite prisms (to 1 mm).
Goodchild, of the Scottish Geological Survey, found wulfenite there in 1875 but the locality only really became of interest to collectors in the 1950s following the reporting of a suite of rare supergene minerals including bayldonite, duftite
, beudantite, carminite, lindgrenite and stolzite (the first authenticated British occurrence).
Associated phases were bayldonite, duftite
, gartrellite, agardite, mimetite and various arsenic-bearing members of the jarosite supergroup.
Associated minerals are: chalcocite, wulfenite, duftite
, "[beta]-duftite" (calcian conichalcite), "cuproadamite" and olivenite.
Tsumeb has produced thousands of dioptase specimens containing sharply formed, translucent to transparent crystals to 5 cm, typically on white calcite or dolomite and occasionally associated with cerussite and duftite
. Fine dioptase specimens in stout, translucent crystals to 2 cm in vuggy massive dioptase and as individuals on white calcite and quartz were recovered in the early 20th century from the Rodgerberg mine near Guchab station, about 15 km east of the Kombat mine (Henglein, 1921).
Small clusters (0.3 mm) of dark red-brown duftite
, consisting of minute (0.01 x 0.07 mm) blades, were observed with wulfenite on small milky quartz crystals from a specimen collected in one of the upper trenches.
And I also saw a few fine specimens of azurite or cerussite (or both) on botryoidal duftite
from Touissit: a new one on me.
Like duftite, bindheimite has been found only in one specimen, as white earthy pseudomorphs after acicular crystals of lead sulphoantimonides.
Apple-green, earthy duftite associated with bindheimite has been found in a single specimen from the Tognetti quarry.
The mineralogy and geochemistry of this gossan have been described by Nickel (1982), who noted the occurrence of a number of secondary ore minerals including malachite, azurite, chrysocolla, pseudomalachite, cerussite, alunite, jarosite, plumbojarosite, osarizawaite, plumbogummite, duftite
, mimetite, fornacite, wulfenite, mottramite, iodargyrite, native silver and a silver-mercury amalgam.
Some superfine, enormous cerussites were sold before I got there, but when I arrived the room still held some excellent small fishtail cerussites from both the Tsumeb and Kombat mines, Namibia, some fine Tsumeb calcite rhombohedron specimens with green duftite
inclusions, a couple of super Tsumeb wulfenite thumbnails, and many rarities for the specialized specialist, e.g., bayldonite, hydrocerussite, ludlockite, schneiderhohnite (!) and molybdofornacite.