Goethite

specimen number:
2262325

location:
Ironwood, Gogebic Co., Michigan, USA

description:
A neat grouping of radiating lustrous goethite crystals. This is in great condition all around. Really nice for this American classic.

The Ironwood mining district, located within the Gogebic Iron Range in Gogebic County, Michigan, was a highly productive and deep underground iron ore mining center. Geologically, the deposit is hosted within the Paleoproterozoic-age Ironwood Iron-Formation, a thick sequence of cherty iron-formation that was heavily tilted, faulted, and intruded by Keweenawan-age diabase dikes. Hydrothermal fluids circulating along these structural intersections leached away silica, concentrating the primary iron minerals into massive, high-grade bodies of soft, red hematite and hard, steel-blue specularite. Historically, the outcropping iron ore was discovered in the area during the early 1880s, triggering a rapid mining boom and the formal incorporation of the city of Ironwood. Large-scale corporate industrial operations commenced in 1884 with the opening of the legendary Norrie Mine, which quickly evolved into an immense complex of deep underground vertical shafts, including the East Norrie, Aurora, Pabst, and Newport mines, operated by major firms like the Oliver Iron Mining Company. These highly mechanized underground works produced millions of tons of high-grade direct-shipping ore annually to supply Great Lakes steel mills, until high pumping costs, deep-level structural complexities, and the widespread availability of cheaper, open-pit taconite operations in Minnesota rendered deep mining uneconomic. This caused a steady contraction of the local industry, culminating in the permanent closure of the Geneva Mine in 1965 and the Peterson Mine in 1967, which marked the final cessation of all commercial iron mining operations along the Michigan portion of the range.

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