Gwindel, smoky quartz, Adular – Val Giuv, Graubünden, Switzerland
 A slightly brownish-smoky crystal. This rare quartz variety exhibits flawless transparency. The end faces are lightly dusted with chlorite, creating a beautiful, three-dimensional contrast against the highly lustrous prism surfaces. The clearly defined crystal is accompanied by a few crystals of the normal habit.
 The Val Giuv, near Sedrun in the Surselva region of the canton of Graubünden, has always been synonymous with the special color and quality of Swiss smoky quartz, which distinguishes it from other quartz.
 Under the most difficult conditions, the crystals are recovered by the prospectors at an altitude of approximately 3,000 meters.