Quartz (gwindel), Actinolite, adularia

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The Mineralogical Museum, University of Delaware

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Quartz gwindel, 8.9 cm, from the Gotthard Massif, Switzerland. These crystals are found in a belt in the fractured granites of the Aare and Gotthard massifs, along with quartz crystals that do not show this morphology. The specimen shown here is of a type known as an “open” gwindel, indicated by the stepped or saw-tooth edges which are not present on “closed” gwindels. There is currently no consensus about how these crystals form. The specimen shown here has an illegible Kunz label, and the card catalog contains many quartzes from various Swiss localities, but the associated actinolite needles and adularia crystals on the back of the specimen suggest that the Gotthard massif, in the eastern part of the central Alps, is the locality.