WULFENITE

ABOUT THE SPECIMEN

Dozens of super sharp, light brown, water clear wulfies sitting on top of a dark matrix. These blades are well defined for the iconic Tsumeb Mine, with sharp beveled edges, and their color is characteristic for the locale. Many of them are pristine, only a couple broken crystals and some with minor edge wear. A few of the crystals diffract light into rainbow prisms, so under the right lighting this is a super colorful specimen!

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Among the secondary lead minerals produced by Tsumeb's supergene oxidation, wulfenite stands out for the sheer breadth of what a single locality can express within one species. Fluid inclusion homogenization temperatures from Gilg et al. (2003) constrain crystallization to roughly 55°C - the low end of supergene conditions - with molybdate ions precipitating from descending fluids reacting with lead-rich carbonate host. The dominant habit is thick tabular with beveled edges imparted by pyramid face modification, typically in caramel orange to sherry-brown; the most productive horizon was the interval between 28 and 32 Levels in the second oxidation zone, where Bartelke's documented pocket finds of the mid-1970s included wulfenite with dioptase and wulfenite on tennantite. A rare and scientifically contentious subset produces deep blue to blue-gray crystals with steep pyramidal to prismatic habits, informally termed "chillagite"; Embrey et al. (1977) disputed the tungsten-bearing interpretation applied by analogy to Australian chillagite, instead attributing the color to partial reduction of Mo⁶⁺ to Mo⁴⁺. Pinch and Wilson documented the full color range as spanning colorless through pink, yellow, orange, greenish-brown, light blue, and very dark blue - a color and habit diversity unmatched by any other single wulfenite locality. With the mine permanently closed since 1996 and all material now old-stock, the blue crystals in particular represent one of the more genuinely rare subsets in the broader Tsumeb secondary mineral suite.