Malachite replacing Azurite

specimen number:
8282033

location:
Kerrouchen, Khenifra, Morocco

description:

Large thick double terminated grouping of what were once azurite crystals now replaced by green malachite. Brecciated matrix is attached on one side. This is in super condition all around. The quality is excellent for this locality.

The Kerrouchen locality, situated in the Khenifra Province of the Beni Mellal-Khenifra region in Morocco, is a well-known copper and lead mining area famed for producing exceptional collector specimens of secondary copper minerals, particularly malachite and azurite. Geologically, the deposit is hosted within Paleozoic sedimentary rocks, predominantly sandstones and shales, that were subjected to intense structural deformation and faulting during the Variscan orogeny. Hydrothermal fluids circulating through these fault systems deposited primary sulfides, which subsequently underwent profound supergene weathering and oxidation under arid climatic conditions, converting the primary ores into rich carbonates within localized solution cavities and veins. Small-scale mining and exploratory quarrying for copper ore by local tribes and early prospectors began in the mid-twentieth century, with the most significant period of organized artisanal extraction and specimen recovery occurring between the 1970s and the 1990s. While large-scale industrial mining has not been sustained, independent local diggers sporadically work the old surface cuts and shallow shafts to supply high-quality mineral specimens to international markets into the 2020s.

A pseudomorph is a mineral that has replaced another species chemical-by-chemical while perfectly maintaining the exact crystal habit, shape, and external geometry of the original mineral. In a malachite-after-azurite pseudomorph, changes in ambient groundwater chemistry, pH, or local carbon dioxide concentrations cause the chemically less stable azurite to convert into the more stable copper carbonate, malachite. This gradual replacement occurs at the structural level, leaving a specimen that showcases the sharp, prismatic, or bladed crystal habits characteristic of azurite, but composed entirely of fibrous or velvety green malachite. The pockets at Kerrouchen are globally recognized for yielding some of the most striking examples of these pseudomorphs, highly prized by collectors for their sharp geometric definitions and rich emerald-green coloration.

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