Manganite with Barite

specimen number:
8311544

location:
Montreal Mine, Iron Co., Wisconsin, USA

description:

Superb lustrous black crystals of manganite across the top of matrix with white barite. In good condition with very minimal damage present. In very fine example of the species from this long closed and important locality.

The Montreal mine, located just west of Hurley in Iron County within the historic Gogebic Iron Range of Wisconsin, United States, was a massive, ultra-deep underground industrial operation that ranked as one of the largest and deepest producers of iron ore in the entire Lake Superior region. Geologically, this immense deposit is hosted within the Paleoproterozoic-age Ironwood Iron-Formation, where steeply dipping, primary banded chert and iron oxide sequences were subsequently altered and concentrated into high-grade, secondary hematite and goethite bodies by deep-circulating meteoric fluids that were structurally trapped against cross-cutting Keweenawan-age basaltic dikes and faults. Historically, commercial operations began in 1886 under the management of the Montreal Mining Company, later coming under the long-term direction of the prominent industrial firm Oglebay Norton and Company, which systematically expanded the workings to include the famous number five shaft, a vertical steel structure that eventually reached an astonishing depth of nearly 4000 feet below the surface. The mine operated continuously for nearly eighty years, serving as a critical strategic resource for the domestic steel industry during both World Wars and supporting a thriving local company town until shifting economics, high pumping costs, and the rising dominance of open-pit taconite mining led to its permanent closure in August 1962.

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