Malachite after Azurite

specimen number:
9506718

location:
Tsumeb mine, Otjikoto, Namibia

description:

Classic Namibian specimen with two thick crystals of what were once azurite, these now replaced by green malachite, forming an aesthetic cluster with little attached matrix. In super condition.

The Tsumeb Mine, located in the Otavi Mountains of northern Namibia, is a world-renowned polymetallic ore deposit hosted within Precambrian carbonate rocks. Geologically, the deposit formed within a steeply dipping, pipe-like structure created by intense tectonic activity, karstification, and hydrothermal fluid circulation. It is celebrated globally for its extraordinary mineralogy, featuring hundreds of distinct mineral species—including dozens found nowhere else on Earth—owing to deep oxidation zones that produced exceptional secondary crystal specimens. Indigenous peoples initially utilized surface outcrops for copper, but large-scale industrial mining began in 1897 under German colonial rule, turning the site into a massive producer of copper, lead, zinc, and germanium until its final closure in 1996.

A pseudomorph occurs when one mineral replaces another while preserving the original crystal shape and form of the first mineral. In the specific case of malachite after azurite, the copper carbonate mineral azurite is gradually altered and replaced by malachite, another copper carbonate, due to changing chemical conditions in the oxidation zones of copper deposits. This chemical transformation retains the distinct crystal habit and sharp geometric forms of the original azurite crystals, but completely changes their classic deep blue color into a vibrant emerald green. Famous localities for this classic specimen type include Chessy-les-Mines in France, Tsumeb in Namibia, and various copper districts in the southwestern United States.

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