Polybasite

specimen number:
2273029

location:
Guanajuato, Mexico

description:
A fine and choice thumbnail specimen of polybasite from this well-known Mexican locality. The specimen comes with a previous label from the A. E. Seaman Mineral Museum at Michigan Tech University. This is shown at the end of the video. In very good condition.

The Guanajuato mining district, situated in the central highlands of Guanajuato, Mexico, is one of the world's most historic and prolific silver and gold producing regions. Geologically, it is a classic epithermal low-sulfidation vein system hosted within a thick sequence of Mesozoic metamorphic rocks and Tertiary volcanic formations. The mineralized structures are dominated by three major parallel fault systems, most notably the Veta Madre (Mother Lode), which reaches widths of up to 40 meters and carries rich silver sulfides like acanthite alongside native gold. Silver was first discovered by Spanish prospectors in 1548, sparking the establishment of legendary operations such as the Valenciana and Rayas mines. Mining operations intensified throughout the colonial era, making Guanajuato the source of a significant portion of global silver production during the eighteenth century. Despite disruptions from the Mexican War of Independence, commercial underground mining and milling operations adapted to modern flotation and cyanidation techniques during the twentieth century and continue actively into the present day.

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