Defernite

Defernite is a very rare lead–iron–chloride–silicate mineral, known from only a handful of localities worldwide. The Kombat Mine, near Grootfontein in northern Namibia, is one of the classic sources. The mine operated primarily as a large copper–lead–silver producer, exploiting carbonate-hosted ore bodies within the Otavi Mountainland. While famous for fine azurite, dioptase, and smithsonite specimens, it also yielded small but scientifically important occurrences of rarities like defernite.

Crystals of defernite from Kombat are typically microscopic and occur in association with altered galena and secondary lead minerals within oxidized zones of the deposit. Collectors value these specimens not for their aesthetic qualities, but for their extreme rarity and mineralogical significance, as examples of the unusual geochemistry that characterizes the Otavi deposits. This specimen comes from the collection of Robert Yeoman, an Irish-born mineral collector who has spent much of his life in Toronto. Over the years, he assembled a diverse and well-regarded collection, particularly notable for its exceptional specimens from Tsumeb and classic Irish localities.