Fluorite

specimen number:
1052702

location:
Haslach im Kinzigtal, Ortenaukreis, Freiburg, Baden-Wurttemberg, Germany

description:
Wonderful large old German classic with purple lustrous slightly translucent cubic crystals of fluorite measuring to almost 7.0 cm in size across the top of matrix. Very little leaving and damage present, overall in good condition. Previously specimen had been in the collection of Wilhelm Hoyer and dates to the 19th century. The specimen comes with a previous antique label as shown at the end of the video. Incredibly fluorescent under longwave ultraviolet light.

The Haslach im Kinzigtal mining area, located within the central Black Forest (Schwarzwald) region of Baden-Wuerttemberg, Germany, is a historic polymetallic district celebrated for producing striking, intense deep purple cubes and bands of fluorite during its peak nineteenth-century operations. Geologically, this classic locality is characterized by hydrothermal vein systems hosted within Paleozoic-age granitic and gneissic basement rocks, which were heavily fractured during Alpine tectonic events. These deep fault fissures served as conduits for mineral-bearing fluids that precipitated thick veins of baryte and fluorite, frequently associated with silver-bearing galena, chalcopyrite, and secondary copper minerals, with the vibrant purple coloration of the fluorite resulting from localized lattice defects induced by natural trace radiation. Historically, small-scale underground mining for silver and copper began in the region during the thirteenth and fourteenth centuries, but the district experienced a major industrial transformation in the nineteenth century, specifically between 1810 and 1895, as the focus shifted toward extracting fluorite and baryte for chemical and metallurgical fluxing. Active operations at prominent local mines, such as the Gott mit Uns and Segen Gottes concessions, systematically extracted highly valued fluorite ore until dropping global market prices and the exhaustion of accessible veins led to a steady decline and eventual closure of major commercial extraction by the turn of the twentieth century.

Wilhelm Hoyer (1849-1913) was a prominent German engineer and mineral collector based in Hanover, whose professional work in railway construction and geology facilitated the assembly of a significant mineralogical collection. Geologically, Hoyer was noted for his deep expertise in the Mesozoic formations of northwestern Germany, particularly the Hildesheim area, where he meticulously documented and collected specimens from active quarries and construction sites. His collection was scientifically important for its comprehensive representation of regional minerals and fossils, reflecting the systematic approach of 19th-century European collectors who bridged the gap between industrial mining and academic mineralogy. Historically, Hoyer was active in the latter half of the 1800s and early 1900s, contributing numerous papers to geological societies and maintaining professional ties with major institutions of his era. Following his death, his extensive mineralogical and paleontological holdings were integrated into the collections of the University of Gottingen and the Prussian Geological Survey in Berlin, where they continue to serve as vital reference materials for researchers through 2026.

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