Namuwite

minerals

schulenbergite

devilline

langite

Formula: Zn4(SO4)(OH)6.4H2O
Hydrated sulphate containing hydroxyl
Specific gravity: 2.77
Hardness: 2
Streak: Pale green
Colour: Sea green

Hydrothermal environments

Namuwite is a very rare secondary mineral; it is a post-mining phase, typically formed through the oxidation of sphalerite-bearing veinstone in mine workings and within zinc and copper rich mine dumps (MW). Associated minerals include hydrozincite, schulenbergite, serpierite, ktenasite, devilline and gypsum (HOM).

Localities

At the Frongoch Mine, Devil's Bridge, Ceredigion, Wales, UK, namuwite occurs very rarely as crystal clusters to 0.5 mm on quartz-galena veinstone. It is clearly post-mining in origin and late in the paragenesis, typically overgrowing langite, wroewolfeite, susannite or hydrocerussite (MW).

At the type locality, the Aberllyn mine, Betws-y-coed, Gwydyr Forest area, Conwy, Wales, UK, namuwite occurs encrusting hydrozincite (Dana) on a breccia composed of slate fragments cemented by sphalerite, quartz, calcite and ankerite (AM 81.238-243, Mindat, MW).

At the Dylife Mine, Penegoes, Powys, Wales, UK, namuwite is associated with schulenbergite on altered sphalerite (MW).

At Balmat, St Lawrence county, New York, USA, namuwite is associated with magnetite (Minrec 41.6.536).

Common impurities: Cu

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