Malachite after Azurite

$3,000.00

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635 sold last year · median $850.00 · last sale $400.00

Weinrich MineralsFeatured

109 for sale·231 sold

Outstanding pseudomorph specimen for this Namibian locality. Large thick prismatic terminated crystals of azurite coming off matrix and replaced by green crystallized malachite. This is in super condition all around.The Onganja Mine, located in the Khomas Region of central Namibia, is a legendary locality famous for producing some of the worlds finest crystallized copper minerals. Geologically, the deposit is a hydrothermal vein system hosted within the metamorphic rocks of the Damara Belt, specifically mica schists and quartzites. The mineralization occurred during the Pan-African orogeny, where copper-rich fluids deposited primary sulfides like chalcocite and chalcopyrite, which were later altered in the oxidation zone to form spectacular secondary minerals. Historically, the mine was first developed in the early 1900s during the German colonial period, with major industrial activity occurring between 1971 and 1975 under the management of Zapau. While the mine has been worked intermittently on a smaller scale since the late 1970s, it remains most famous for the massive, lustrous cuprite crystals and exceptional malachite specimens recovered during its brief but prolific mid-century peak.A pseudomorph is a mineral that appears in the external shape of another mineral species, essentially a chemical replacement that preserves the original crystal form. At the Onganja Mine, the replacement of azurite by malachite is a classic example of this process, occurring as carbonated waters react with the primary copper ore. In these specimens, the original sharp, tabular, or prismatic crystals of azurite (a copper carbonate) become unstable and are replaced atom-by-atom by malachite. The result is a specimen that possesses the distinct, often large and blocky, crystal habit of azurite but consists entirely of the velvety green, fibrous, or silky aggregate of malachite. These replacements are highly sought after by collectors because they capture a specific moment in geological time when the chemical environment of the ore body shifted, leaving behind a green mineral "ghost" of the former blue crystal.