Goethite

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Very choice lustrous black botryoidal goethite specimen. In great condition and quite nice for this locality. The Steep Rock mine, situated near Atikokan in the Rainy River District of Ontario, Canada, was a monumental open-pit and underground iron mining operation that required one of the largest engineering and river-diversion projects in Canadian history. Geologically, the deposit sits within the Archean-aged Steep Rock Group of the Superior Province, where a major unconformity features a thick basal conglomerate overlain by a massive carbonate platform and the volcanic Ashrock Formation. Hydrothermal alteration along major fault zones transformed portions of these volcanic and sedimentary sequences into a vast, high-grade iron orebody dominated by structural zones of dense goethite and hematite beneath the waters of Steep Rock Lake. To access the ore, engineers famously diverted the Seine River system and pumped billions of gallons of water out of the lake during World War II, allowing open-pit mining to officially begin in 1944. Full-scale commercial shipments launched in May 1945, with underground shaft operations added in 1953 to extract deeper horizons as the surface pits expanded. The mine operated continuously as a backbone of the regional economy for over three decades until depletion of the economically recoverable reserves and shifting pellet technologies led to the permanent cessation of all mining activities in 1979.