Slate has been extract in the Sernft valley in eastern Switzerland since the sixteenth century. Exporting was restricted by lack of a road into the valley, and the produce of the mines and quarries was taken away on the backs of mules until a road was built in 1826. More than 200 men were employed in the quarries by 1826. Extraction ceased in 1961, but the Stiftug Landesplattenberg, a non-profit body to preserve the mines for the future was established in 1994. Since 1995 visitors have been able to participate in guided tours lasting two-and-a half-hours, beginning at the mine entrance at Hinterdorf Engi. The tours pass through vast caverns whose roofs are supported by pillars of slate left by the miners. Some caverns are occasionally used for concerts. The slate mine is part of the UNESCO World Heritage Site Swiss Tectonic Arena Sardona.
Fossils from the slate deposits discovered from 1705 by the celebrated Zurich geologist Johann Jakob Scheuchzer (1672-1733) were distributed to natural history museums all over the world, and some examples can be seen in the Glarner Naturmuseum opened in 2004 in a former textile mill in nearby Verderdorf.