Wurtzite

specimen number:
9302322

location:
Rachelshausen, Hessen, Germany

description:
Small crystals of wurtzite on matrix. In good condition, nice example for the species.

The Rachelshausen locality, located near Gladenbach in the Marburg-Biedenkopf district of Hessen, Germany, is a historical mining area noted for its localized mineralized zones. Geologically, the deposit is situated within the Rhenohercynian Zone of the Variscan Orogeny, where Paleozoic sedimentary sequences including shales, graywackes, and limestones are cut by late-stage hydrothermal veins. These low-temperature vein systems precipitated a variety of base metal sulfides and carbonatite-associated minerals within fractures and brecciated zones. Small-scale mining for iron and copper occurred intermittently in the region from the late medieval period through the nineteenth century, with exploratory and localized quarrying operations ceasing entirely by the early twentieth century.

Wurtzite is a zinc iron sulfide mineral that represents the high-temperature, hexagonal polymorph of zinc sulfide. Geologically, it typically forms in low-to-medium temperature hydrothermal veins, sedimentary exhalative deposits, or as a secondary precipitate in low-temperature ground water environments, often forming as hemimorphic, pyramidal crystals or fibrous, radiating acicular aggregates. The mineral is structurally distinct from its isometric dimorph, sphalerite, and is highly prone to polytypism, meaning it can form numerous layered stacking variations within its crystal lattice depending on the specific temperature and chemical conditions during crystallization.

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