Gerhardtite

specimen number:
9302302

location:
Likasi, Kambove, Katanga, DR Congo

description:

A set of two good examples of the rare mineral gerhardtite. size provided for the larger of the two examples.

The Kambove mining district, situated approximately 25 kilometers northwest of Likasi within the Haut-Katanga Province of the Democratic Republic of the Congo, is a major copper and cobalt producing region located along the Central African Copperbelt. Geologically, the deposits are sediment-hosted stratiform systems situated on the southern flank of a large, north-verging syncline within the Neoproterozoic Mines Subgroup of the Roan Group, where intense folding, thrusting, and halokinetic evaporite deformation shaped the strata. Primary copper and cobalt mineralization occurs as stratiform laminations and disseminations of chalcocite, bornite, chalcopyrite, and carrollite within dolomitic shales, siltstones, and dolostones, which underwent extensive supergene enrichment near the surface. Commercial-scale exploitation by the Union Miniere du Haut-Katanga began around 1926 with open-pit steam shovel operations, expanding into selective underground mining at Kambove West during the late 1930s to target deeper sulfide ore bodies. Following nationalization into the state-owned enterprise Gecamines in the 1960s, extraction from various open pits and underground shafts fluctuated through peak production phases and subsequent infrastructure challenges, with active mining operations and exploration continuing into the twenty-first century.

Gerhardtite is a rare secondary copper nitrate mineral that forms in the highly oxidized portions of copper deposits. It typically occurs as dark emerald-green to bluish-green tabular crystals, radiating crystalline crusts, or fibrous aggregates derived from the alteration of primary copper sulfides in arid environments or protected mine workings. Notable for its deep pleochroism and perfect cleavage, the mineral serves as an indicator of specialized localized environments where nitrate concentrations are sufficient to stabilize secondary copper salts.

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