Diaspore

specimen number:
2354190

location:
Gloucester Farm, Postmasburg, Northern Cape, South Africa

description:
Purplish red lustrous crystallized diaspore in a cluster with little attached matrix. This is the manganese rich variety. Classic for this old South African locality and species. The specimen comes with a previous label from the collection of Jack Nieburger.

Situated in the Postmasburg manganese field of the Northern Cape, South Africa, the Gloucester Farm locality is hosted within Precambrian ferruginous and manganiferous meta-sedimentary rocks associated with ancient karst weathering and hydrothermal fluids. Mining operations in the district developed during the twentieth century primarily for high-grade iron and manganese ores, exposing unique fracture fillings and open pockets within the surrounding hematite-rich host rock. The site became renowned among mineral collectors for producing exceptional specimens of diaspore, which typically forms well-crystallized, tabular to prismatic crystals with distinct vitreous to pearly luster and rich brownish-purple, pink, or grayish colors. Although active industrial mining focused on bulk metallic ores, specimens recovered from Gloucester Farm remain highly prized in private collections as benchmark regional examples of aluminum oxide hydroxide crystallization.

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