Fluorite with Calcite

specimen number:
9506141

location:
La Collada, Siero, Asturias, Spain

description:

Gemmy blue glassy crystals of cubic fluorite to 4.0 cm on edge across the top of a calcite matrix. Some cleaving is present as shown close in the video, this still in a non-prominent area and I think overall the specimen is in good condition.

La Collada in Siero, Asturias, Spain, is a prominent fluorite-producing mining area whose industrial history began around 1904 when mineralized veins were first identified, leading to systematic commercial exploitation from the 1930s onward through companies like Fluoruros S.A. Operations across various sector systems and crosscuts continued through the decades before major underground works closed in 1977, though localized open-pit and specimen-recovery efforts have continued intermittently into the 21st century. Geologically, the district belongs to the Central Carboniferous Basin and the Cantabrian Zone, featuring mineralization concentrated in veins, fractures, and stratabound bodies. The host rocks primarily comprise Paleozoic Carboniferous limestones and unconformably overlying Permo-Triassic red-bed siliciclastic sediments, marls, and carbonates, where hydrothermal fluids deposited rich associations dominated by fluorite alongside calcite and quartz.

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