AZURITE & BAYLDONITE

ABOUT THE SPECIMEN Classic example of Tsumeb mineralogy! Sharp blue azurite crystals, partially pseudomorphing to malachite, grown together with an abundant group of the rare lead-copper arsenate bayldonite. The contrast of the deep blue with the multiple shades of green gives it what I can only describe as an alluring appearance. When one finds Tsumeb specimens of bayldonite, it's usually with patchy coverage and much duller color. Here we have rich and attractive minty green color, and the coverage is continuous throughout the whole specimen. There are a couple of other species present, though we haven't had it analyzed.   VIDEO   MORE INFO Bayldonite is a lead copper arsenate hydroxide confined almost entirely to Tsumeb's first oxidation zone - the water table fluctuation zone above the 11th Level - where the full complexity of the deposit's supergene chemistry produced the arsenate-rich, lead-copper environments the species requires. Southwood's 2025 Rocks & Minerals treatment confirms that bayldonite most commonly occurs at Tsumeb as a pseudomorph after mimetite, retaining the hexagonal prismatic outline of the precursor in oil-green to grass-green powdery to microcrystalline coatings; pseudomorphs after azurite, tennantite, and wulfenite are documented but considerably rarer. The combination of bayldonite pseudomorphs after mimetite as matrix, overgrown by sharp tabular azurite crystals, produces some of the most mineralogically layered specimens the deposit ever yielded - two sequential supergene stages preserved on a single piece. The earliest documented material predates 1920, and the first oxide zone was largely consumed by mining before mid-century. With the mine permanently closed since 1996 and the 2000s Ongopolo recovery effort yielding only marginal specimen production before abandonment in 2008, confirmed bayldonite-azurite combination pieces from well-documented early extraction are among the more scientifically significant subsets in the broader Tsumeb secondary mineral suite.