The Idaho Cobalt Belt (ICB) is a northwest-trending zone of cobalt-copper-gold (Co-Cu-Au) occurrences, at least 64km long and up to 10km wide, centered on Jervois’ Idaho Cobalt Operations (“ICO”).
The ICB is a unique example of sea-floor hydrothermal brines that vented along an ancient rift within a deep-water setting, providing a distinctive geochemistry. It is an exceptional metallogenic province in which cobalt is the primary metal in the deposits due to its sufficiently high concentrations.
The deposits are mostly strata-bound and appear to have formed during a mafic volcanogenic-exhalative mineralizing event on a paleo-sea floor, ~1600 million years ago. More recent regional metamorphic events have remobilized Cu and, to a lesser extent, Co in varying degrees throughout the belt. The deposits are unusually rich in Co, Cu, Fe, As, Au, B, Bi and light rare earths, but low in Ni (relative to Co), Ag, Pb, and Zn. The synsedimentary controls, mineralogy and geochemistry are unusual among ore deposits, though similar features in some other deposits are known.
Sediment-hosted deposits are major ore producers in the world, but unlike the ICB, most tend to be Pb and Zn rich. Some sediment-hosted deposits that contain Cu also contain Co – notably, the deposits of the Katanga province of the Democratic Republic of the Congo (DRC) and the adjoining Zambian Copperbelt deposits. Significant differences exist between deposits in these west African deposits and the ICB, whereas many intriguing similarities are found between ICB deposits and Sullivan, Canada, and Mount Isa and Broken Hill, Australia.
The ICB is currently known to host several Co-Cu deposits within several sequences of metamorphosed, mafic volcaniclastic rocks. ICO encircles the inactive Blackbird mine and encompasses the deposits and more than a dozen underexplored prospects and exploration targets.