Orthoclase

specimen number:
2072196

location:
Valenciana Mine, Guanajuato, Mexico

description:
Classic material for this famous Mexican locality. White crystals of orthoclase measuring to 1.5 cm in size are covering the top of this matrix. This is the variety often called valencianaite, and at one time was thought to be adularia or albite. In very good condition. Previous label from the collection of Wolfgang Henkel.

The Valenciana Mine, situated on the Veta Madre (Mother Lode) in Guanajuato, Mexico, was once one of the most productive silver mines in the world. Geologically, it is a classic epithermal vein deposit hosted within a complex structural system of faulted Mesozoic volcanic and sedimentary rocks. The primary mineralization occurred when silver-rich hydrothermal fluids filled massive fissures, creating veins of quartz, calcite, and adularia containing silver sulfides like acanthite and various sulfosalts. Historically, the mine began its legendary ascent in 1760 when Antonio de Obregon y Alcocer discovered a rich ore shoot, leading to a period of immense wealth that helped fund the Spanish Empire. At its peak in the late 18th century, Valenciana produced nearly a quarter of the world's silver. Operations continued through various cycles of boom and bust, including significant modernization in the 19th and 20th centuries, before large-scale commercial extraction eventually transitioned to smaller operations and tourism. Today, the mine is part of a UNESCO World Heritage site, recognized for its architectural grandeur and its pivotal role in global mining history.

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