Seafloor Miners Poised to Cut into an Invisible Frontier – by Julian Smith (Scientific American – August 11, 2016)

The ocean floor teems with mineral treasures, but extracting them could jeopardize an unexplored alien world

People have been clawing valuable minerals like iron and gold out of the ground for millennia. And for much of the stuff that touches our lives today — from the europium, terbium and yttrium that help illuminate the screen you are reading to the copper in the wires that power it— we increasingly depend on elements from the depths of the Earth. But finding new deposits gets harder every year and mines are steadily growing larger, more expensive and more environmentally destructive.

On land, that is. By some estimates the ocean floor has the planet’s largest resources of minerals such as copper, nickel and cobalt. The deep sea also holds gold, silver, platinum and the rare earth elements used in high-tech devices and renewable-energy technology including iPhone displays, solar panels and magnets used in hybrid cars.

Underwater deposits often have much higher grades of ore than those on land, meaning they contain a higher percentage of the desired minerals—in some cases by an order of magnitude or more. The trick is getting the stuff to the surface in a cost-effective way.

Canadian mining firm Nautilus Minerals says it plans to lead the way with the world’s first commercial deep-sea mining project, scheduled to get underway within the next few years off the coast of Papua New Guinea.

The idea of mining the seafloor goes back at least to 1870when Captain Nemo in Jules Verne’s novel 20,000 Leagues under the Sea declared, “In the depths of the ocean, there are mines of zinc, iron, silver and gold that would be quite easy to exploit.”

Only recently has deep-sea mining become technologically and financially feasible, thanks to using remotely operated subs and other technologies developed for deepwater oil and gas production. Proponents say higher ore grades mean deep-sea mining would be more cost-effective than land-based operations, with a smaller ecological footprint that would be less visible.

But these are uncharted waters, says Cindy van Dover, director of the Duke University Marine Laboratory in Beaufort, N.C. “We do not know where the tipping points are with regard to how much damage deep-sea systems can sustain and still maintain the health of the ocean,” she says.

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