Dolomite

specimen number:
1052601

location:
Lengenbach Quarry, Binn Valley, Valais, Switzerland

description:
Colorless gemmy rhombohedral crystals of dolomite measuring to 1.7 cm in size across the top of matrix. In good condition. Very choice Swiss classic, the specimen comes with an antique label as shown at the end of the video. This label provides an acquisition date for the specimen in 1908.

The Lengenbach quarry, situated within the famous Binn Valley of Valais, Switzerland, is an internationally celebrated mineral locality globally renowned for producing exceptional, highly lustrous, and beautifully twinned colorless dolomite crystals alongside its complex suite of rare lead-arsenic sulfosalts. Geologically, these gemmy, rhombohedral crystals are hosted within a highly unique, Triassic-age dolostone band that underwent intense, localized tectonic deformation and low-grade, fluid-dominant metamorphism during the Alpine orogeny. This intense metamorphic activity forced hot, highly specialized hydrothermal fluids through the dense carbonate strata, leaching magnesium and calcium to slowly precipitate exceptionally sharp, water-clear dolomite twins inside low-pressure open cavities and structural fissures. Historically, organized small-scale quarrying at Lengenbach began in the early nineteenth century, around 1803, initially focusing on the extraction of iron ores before shifting entirely toward scientific specimen recovery managed by local syndicates and museum expeditions. Formal, seasonal open-cast quarrying operations ran with various degrees of consistency through the nineteenth and twentieth centuries, transitioning into a strictly controlled, scientifically driven specimen operation overseen by the Lengenbach Research Association starting in 1958.

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