Kennecott Utah Copper said it has uncovered a massive molybdenum deposit underneath its Bingham Canyon mine in Utah, US.
The deposit is estimated to have 500 million tonnes of molybdenum.
Kennecott is not sure whether it would be feasible to build a mine to extract the deposit and is currently executing an open-pit mining operation that is scratching the deposit's surface, despite the highest value ore sitting nearly 1,500ft beneath the pit bottom.
Kennecott parent company Rio Tinto announced last year a proposal to invest $270m to construct a unit for deep processing and refining of molybdenum ore found at the Utah mine.
Molybdenum is a silvery-white metal that is a by-product of copper output. It is used in high-strength steel alloys and is a key constituent in oil refining.