Hausmannite

specimen number:
9302325

location:
Ilfeld, Harz, Thuringia, Germany

description:

Fine thumbnail sized example for the species from this classic German locality. In good condition.

The Ilfeld mining district, situated in the Harz Mountains of Thuringia, Germany, is globally renowned for producing historic manganese mineral specimens, particularly manganese oxides. Geologically, the deposit consists of low-temperature hydrothermal veins that crosscut Permian-aged volcanic rocks, primarily melaphyre and porphyry, within the southern Harz boundary fault zone. These specialized veins filled open fissures with crystalline manganese oxides, barite, calcite, and iron oxides during late-stage igneous and tectonic activity. Commercial underground mining operations for iron and manganese ore began in the early eighteenth century, around 1740, and reached peak specimen and industrial production during the nineteenth century. Mining activities declined sharply due to ore depletion and shifting economic factors, leading to the permanent closure of all active manganese mines in the district by 1922.

Hausmannite is a complex manganese oxide mineral that typically occurs as a primary mineral in high-temperature hydrothermal veins and contact metamorphic zones. Geologically, it precipitates directly from manganese-rich hydrothermal fluids or forms through the alteration of earlier manganese silicates and carbonates, often developing as sharp, lustrous pseudo-octahedral crystals, twinned configurations, or granular masses.

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