Goethite

specimen number:
2062212

location:
Tilden Mine, Marquette Co., Michigan, USA

description:
Nice banded goethite example from this old locality.

The Tilden mine, located near the city of Ishpeming within Marquette County, Michigan, United States, is a massive, critically important open-pit iron ore operation noted for its long history of advanced metallurgical innovation. Geologically, this immense deposit is situated within the Paleoproterozoic-age Negaunee Iron Formation of the Marquette Iron Range, a thick sequence of highly deformed, cherty sedimentary rocks containing rich concentrations of both magnetic gray magnetite and non-magnetic red-brown hematite ores. During the mid-twentieth century, as regional deposits of high-grade, direct-shipping hard iron ores faced rapid depletion, extensive research led to pioneering chemical flotation and selective flocculation techniques designed to successfully concentrate these abundant, lower-grade fine-grained taconite iron oxides into high-density pellets suitable for blast furnaces. Historically, small-scale open-pit excavations at the site began as early as 1929, but large-scale, modern industrial quarrying and pelletizing operations officially commenced in December 1974 under the management of the Cleveland-Cliffs Iron Company. While its adjacent sister operation, the Empire mine, was permanently idled in 2016, the highly mechanized Tilden open pits and processing facility have continued running continuously, undergoing several major infrastructural upgrades and waste-rock stockpile expansions through 2026 to sustain a steady domestic steelmaking supply under ongoing life-of-mine projections.

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