Quartz

specimen number:
1052635

location:
Steinkaulenberg, Idar-Oberstein, Birkenfeld, Rhineland-Palatinate, Germany

description:
An open geode half lined with colorless and purple crystallized quartz. Minimal damage present, very nice for this German classic. The specimen comes with a previous antique label as shown at the end of the video. This label notes that at one time the specimen was part of the collection of Wilhelm Hoyer and would date to the 19th century.

The Steinkaulenberg, historically known as Galgenberg, is situated in Idar-Oberstein, Germany, and represents the only gemstone mine in Europe open to the public where minerals are visible in their original host rock. Geologically, the site is part of the Saar-Nahe Basin and consists of Permian-age volcanic rocks, specifically tholeiitic basalts and andesites, that contain numerous amygdules or gas cavities. Over millions of years, silica-rich hydrothermal fluids filled these voids to create geodes lined with deep purple amethyst crystals, often accompanied by agate, smoky quartz, and rare green jasper. Historically, mining and quarrying at this locality began as early as the mid-15th century to supply the regions famous lapidary industry. Industrial underground operations reached their peak during the 18th and early 19th centuries, but commercial mining officially ceased around 1870-1875 when massive Brazilian deposits made local extraction economically unviable. Since 1979, the historical tunnels have been preserved as a visitor mine, allowing for the educational study of situ amethyst formations through 2026.

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