Fluorite

specimen number:
1052703

location:
Weardale, Co. Durham, England, UK

description:
A beautiful grouping of lustrous mostly gemmy cubic fluorite crystals measuring to 8.0 cm on edge. Siderite is rich in association. There is some cleaving and damage present, overall however in good condition. The specimen comes with an antique label as seen with an original acquisition date in 1907. One picture is taken in outdoor sunlight, the other is taken in normal indoor lighting. The old label is shown at the end of the video. The video was taken indoors.

The Weardale mining district, situated within the North Pennines Orefield in County Durham, England, is a globally renowned mineral locality celebrated for producing spectacular, highly transparent crystals of fluorite (calcium fluoride) that frequently exhibit intense, natural daylight fluorescence. Geologically, this world-class deposit is hosted within a thick Carboniferous-age sedimentary sequence of cyclothemic limestones, sandstones, and shales that was intruded by the deep, subterranean Devonian-age Weardale Granite. Hydrothermal mineralizing fluids channeled along deep-seated fault fractures and structural shears reacted with the wall rocks, precipitating thick, vertical veins and extensive horizontal flats rich in fluorite, galena, sphalerite, and quartz, with trace quantities of rare-earth elements like europium substituting into the fluorite lattice to cause its famous purple-to-blue color change under ultraviolet light. Historically, small-scale surface quarrying and primitive trenching for lead ore began during the Roman occupation, with formal underground shaft mining expanding heavily under the control of the Bishops of Durham from the twelfth century onward. The district experienced a massive industrial transformation during the nineteenth century and throughout the twentieth century as commercial focus shifted from lead toward extracting fluorite as an essential flux for the booming British steel industry, with major operations at classic mines like Boltsburn, Heights, and Blackdene running continuously until the closure of the iconic Groverake mine in the summer of 1999 marked the end of traditional commercial industrial extraction.

Ernst August Boettcher (often spelled Boettcher or Boettcher in historical records), operating from Berlin, Germany, during the late nineteenth and early twentieth centuries, was a highly successful natural history dealer and commercial merchant who distributed premier geological, mineralogical, and zoological materials to prominent museums and private collectors worldwide. Inheriting the established firm in 1900 following the death of his father, August Boettcher, he systematically expanded the business under the commercial title Naturalien- und Lehrmittel-Anstalt Ernst A. Boettcher, building a vast trading network headquartered at Bruederstrasse 15 in Berlin. While Boettcher achieved considerable scientific renown in entomology as a specialized collector and describer of lepidoptera, his dealership simultaneously functioned as a major European hub for educational supply suites, offering highly curated collections of minerals, rocks, and paleontological specimens structured specifically for academic instruction in mineralogy and economic geology. His exceptional organizational skill and high-quality educational displays earned the firm a prestigious Gold Medal at the St. Louis World Fair in 1904, solidifying his international reputation. His commercial operations remained highly influential through the 1910s and 1920s, continuing to supply verified European mineral specimens to institutions like the Berlin Natural History Museum, with the enterprise maintaining a registered commercial presence in the Berlin business directories well into the 1940s.

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