Undersea Riches

Science World, Oct 4, 1999 by Sharon Guynup

Daylight slowly fades as the tiny submarine descends beneath the Atlantic Ocean. One thousand feet below, the sea is pitch-black. Even with the sub's powerful lights, visibility is a mere 20 feet. Two hours later, Rutgers University marine geologist Peter Rona and his two-man crew settle down on a high mid-Atlantic ridge, one mile below the surface.

The outlandish marine life--giant white clams, mounds of intertwined spaghetti-like worms, and forests of tubular, human-size creatures swaying in the current--fascinates Rona. "It's otherworldly, like nothing I've ever seen before," he says.

But something else captures Rona's attention. Clusters of slender "chimneys" belch what seems to be black smoke. Most of these chimneys, or "black smokers," rise just a few feet from the seafloor, but several rock formations loom more than 30 meters (100 feet) high. Black and brown, the chimneys glitter with metallic red, orange, and green deposits on their sides. The mineral deposits that form the chimneys are mega-rich in some of Earth's most prized metals: gold, copper, silver, and lead--metals used in everything from fine jewelry to water pipes, telephone lines, and medical equipment (see mineral table).

MINERALS TABLE

Mineral       Gold                     Lead
              (Au)                     (Pb)

Used For      jewelry, spacecraft      batteries, water
              coating, electronics     pipes, gasoline
              coins                    crystal

Found         South Africa, U.S.,      U.S., Australia
              Russia

Cool Facts    Your contains about      The glass screen on
              0.001 grams of gold      your TV contains
              for every kilogram       about 0.23 kg (0.5
              you weigh.               lbs) of lead

Mineral       Silver                   Copper
              (Ag)                     (Cu)

Used For      dentistry, coins,        pipes, wires, the
              photography chemicals    Statue of Liberty's
                                       "skin"

Found         Canada, Mexico,          U.S., Northern
              Norway, Czech            Europe
              Republic

Cool Facts    Silver iodide can be     Copper paint on
              sprinkled over           ships' hulls kills
              clouds to produce        small marine
              rain.                    organisms

GOLD RUSH!

The discovery of untold treasure on the ocean floor has sparked a kind of millennium-style gold rush. But unlike the rush of prospectors who flocked to California in 1849 with pickaxes on their backs, scientists now scour and map seabeds in subs equipped with remote-controlled cameras. In 1998, geologists discovered a trove of gold and silver--its worth estimated at $2 billion!--in the crater of an active undersea volcano 400 kilometers (250 miles) south of Tokyo. And that has Peter Rona and many other scientists concerned.

As miners stake claims to sites of undersea riches, environmentalists worry that seabed mining could destroy the ocean's deep exotic life (see sidebar "Extreme Life"). No international mining regulations exist for this new industry--only the regulations of individual countries within their own coastal waters.

"We've only recently discovered many of these species," says Rona. Some scientists who study these environments think they may be the birthplace of all life on Earth. "If we lose them, we lose valuable secrets to the history of evolution."

But the gold rush is gaining momentum fast. Marine geologists have uncovered mineral-rich volcanic fields in the Pacific, Atlantic, and Indian oceans. Getting at these riches, however, will cost mining companies a fortune. Geologists and engineers will need to develop new technologies to haul the black smokers to the surface so they can extract the precious metals embedded in them.

BLACK SMOKERS

Black smokers are created by undersea volcanic hot springs (see diagram). The chimneys rise from underwater volcanic vents, or fissures, in the Earth's crust. Magma, mineral-laden liquid lava, percolates from the vents at temperatures up to 400 [degrees] C (752 [degrees] F). Highly concentrated minerals called polymetallic sulfides harden into ever-growing chimneys as they hit icy sea water. Since 1977, more than 100 hot springs have been discovered along a 64,000 km (40,000-mi) chain of volcanic fissures that circle the globe like a gold ring.

[ILLUSTRATION OMITTED]

The new gold rush kicked off in 1997, when Papua New Guinea granted a private Australian company, Nautilus Minerals Corporation, permission to prospect for minerals off its coast. The mineral deposits lie in relatively shallow sea water, about a mile down. Some small samples of volcanic rock contain up to 200 grams (7 ounces) of silver and 28 gm (1 oz) of gold per ton, higher than some mineral deposits found on land. Nautilus plans to start hoisting up a wider sampling of volcanic rock from the seafloor within a year.

But mining undersea metals even from shallow waters demands technological wizardry. The formations off Papua New Guinea lie in frigid darkness. Even at one mile deep, the literally crushing water pressure is between 3,000 and 5,000 pounds per square inch. "The pressure can press a car into a little block of metal," says geological engineer J. Robert Woolsey. So how will Nautilus geologists bring up these riches?