Orthoclase from Karlovy Vary Region, Czech Republic

$150.00

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A twinned crystal of prismatic orthoclase measuring 3.0 cm in height set on matrix. In great condition. The specimen comes with two previous labels, one from the collection of Ray DeMark, and the other from Michigan Technological University, Seaman Mineral Museum.Situated in the northwest portion of the Czech Republic, the Karlovy Vary Region sits within the Bohemian Massif, where Variscan granitic intrusions cooled slowly beneath the surface to form coarse-grained crystalline rocks. These granitic formations, particularly around the historic spa city of Karlovy Vary (formerly Carlsbad), became famous among mineral collectors in the nineteenth century for producing distinct penetration twins of potassium feldspar. Known universally in crystallography as Carlsbad twins, these interpenetrating orthoclase crystals were extensively documented and collected during early mineralogical surveys, making the region a historic type locality for studying twinning mechanisms in igneous silicates.