Goethite

specimen number:
2062250

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

description:
Radiating banded crystalline goethite throughout matrix. Good locality example for the species.

The National mine, situated within the city of National Mine in the historic Marquette Iron Range of Marquette County, Michigan, was a notable underground and open-pit iron mining operation. Geologically, the deposit is hosted within the Paleoproterozoic-age Negaunee Iron Formation, a thick, structurally complex sequence of interbedded chert, magnetite, and hematite layers that underwent intense localized folding and secondary enrichment by supergene fluids. These circulating fluids leached away silica and concentrated the iron oxides into massive, high-grade soft hematite and hard specularite orebodies along the axes of synclinal folds. Historically, the property was first opened and developed by the National Iron Mining Company in 1877, with regular rail shipments of high-grade lump ore commencing shortly thereafter to supply Midwestern blast furnaces. The operation expanded through a series of underground shafts and open cuts, maintaining steady production through the late nineteenth and early twentieth centuries before consolidation under larger mining conglomerates like the Cleveland-Cliffs Iron Company. Primary commercial extraction at the National mine property concluded in the mid-twentieth century as high-grade direct-shipping ores reached economic exhaustion, shifting the regional focus toward large-scale taconite pellet production at nearby active mega-complexes.

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