Fluorite with Galena, Calcite, Quartz

specimen number:
2292258

location:
Weardale, Durham, England, UK

description:

Gemmy cubic purple crystals of fluorite measuring to 1.5 cm on edge across the top of a crystallized quartz matrix with minor galena and calcite. The fluorite crystals are brightly fluorescent. Crystallized nicely all around as seen in the video. Minimal micro-cleaving present. Collected in the 1970s.

The Weardale area, situated within County Durham, England, is an iconic mineral locality celebrated for its production of fluorite crystals, including those notable for their intense daylight fluorescence. Geologically, the region is positioned in the northern part of the Alston Block within the Northern Pennine Orefield, where mineralized veins occupy faults and fractures cutting through a thick Carboniferous sedimentary sequence of limestone, sandstone, and shale. Hydrothermal fluids originating from the deep-seated, underlying Weardale Granite circulated through these fractures, depositing fluorite alongside galena, quartz, sphalerite, and iron carbonates. Lead mining in the valley dates back to at least the Roman and medieval eras, transitioning heavily toward industrial-scale fluorite extraction for iron and steel flux during the late nineteenth and twentieth centuries at major underground operations like the Blackdene, Heights, and Boltsburn mines. While large-scale commercial extraction wound down and effectively ceased by the end of the 1990s, specialized specimen mining operations at localities like the Rogerley and Diana Maria mines have continued to systematically recover fine collector specimens well into the 2020s.

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