Hematite with Calcite

specimen number:
2062180

location:
Commonwealth Mine, Florence Co., Wisconsin, USA

description:
neat locality example with crystallized sparkling micro hematite across the top of matrix with crystallized calcite. In good condition.

The Commonwealth Mine, located in Florence County, Wisconsin, was a significant producer of iron ore within the Menominee Range. Geologically, the deposit consisted of high-grade hematite and goethite hosted within the Precambrian-aged Vulcan Iron Formation, where tectonic folding and faulting created concentrated pockets of ore. The mine is notable for its occurrence of massive hematite and occasional pockets of needle-like goethite crystals. Historically, the Commonwealth Iron Company began development of the site in 1880, shortly after the arrival of the Menominee River Railroad made large-scale transport feasible. The mine operated as a major open-pit and underground facility through the late 19th and early 20th centuries, reaching its peak production during the 1890s. While most large-scale operations at the site ceased by the early 1930s due to the depletion of easily accessible high-grade ore, the Commonwealth Mine remains a key historical site marking the expansion of the iron industry into northeastern Wisconsin. Today, the flooded remains of the pit serve as a reminder of the region's industrial heritage and the geological richness of the Menominee Iron District.

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