Mining ocean-floor mineral ore. Offshore seabed deposits are unmapped and untapped

TWENTY years ago, a United States government report noted that ``almost every large [American] mining and aerospace company'' was only ``awaiting the identification of promising areas on the [continental] shelf ... before launching major development programs'' to mine mineral wealth from the sea. They're still waiting. According to the congressional Office of Technology Assessment (OTA), ``With the exceptions of sand and gravel and precious metals, the commercial prospects for developing marine minerals ... appear to be remote for the foreseeable future.''

The vision of sea-floor bonanzas has been an enduring chimera - always intriguing, always economically out of reach. It's no wonder that the OTA study - ``Marine Minerals: Exploring Our New Frontier'' - released last month found that ``only a minuscule portion'' of the United States' offshore exclusive economic zone (EEZ), 200 nautical miles wide, has been explored for minerals. Yet these minerals include strategically important elements such as chromium, which the US must import. It would be wise to identify minable deposits of such minerals to use in an emergency if foreign supplies were cut off.

For decades, there has been little doubt that such deposits exist within the EEZ. But this expectation has been mostly wishful speculation based on a few intriguing discoveries. In 1966, for example, the three-man research submarine Aluminaut, owned by the Reynolds Submarine Service Company, donned wheels to roll along an undersea ``highway'' literally paved with mineral ore.

Located off the southeastern coast of the US, the ``pavement'' is a manganese-rich deposit laid down by the natural chemistry of the sea. This kind of spectacular deposit was often cited to suggest undiscovered vast mineral wealth. We know no more than this, two decades later.

OTA notes that ``little credence should be given to estimates of the economic value or tonnages of seabed minerals that have been inferred by some observers.'' What's needed is a systematic, thorough exploration of the EEZ, which, in area, is two-thirds as large as the continental United States.

There are several kinds of possible mineral deposits besides sand and gravel, which are being mined, and oil and gas, which are not at issue here.

Placers: accumulations of sand, gravel, or both containing gold, platinum, and some other metals.

Polymetallic sulfides: metal compounds formed on the seabed in volcanic areas that contain copper, lead, zinc, and other minerals.

Ferromanganese crusts: cobalt-rich deposits that may also have lesser amounts of other metals such as copper or nickel. (The Aluminaut's ``pavement.'')

Ferromanganese nodules: potato-size rocks similar in composition to the ferromanganese crusts.

Phosphorite beds: seaward extensions of onshore deposits of phosphate rock, useful as fertilizer.

Currently, the US Geological Survey and the National Oceanic and Atmospheric Administration are cooperating in the most extensive exploration and cataloging of the EEZ. But something like a dozen US agencies are involved. OTA notes that this leads more to confusion than to cooperation. Furthermore, data, once gathered, are not always carefully archived in ways that make them accessible for general use.

The United States needs to replace this haphazard surveying of its EEZ with a coordinated effort that will make this undersea domain as well known as the land. Modern depth-measuring instruments and computerized data processing can produce detailed three-dimensional seabed maps to aid prospecting, as well as general oceanographic research.

But there is a major obstacle to doing this thoroughly. The same detailed mapping needed to know and manage the EEZ seabed would also be useful to foreign submarine captains in hiding their subs. Thus the Department of Defense and the civilian oceanographic agencies have been at cross-purposes over seabed mapping for years. The Pentagon wants to keep the maps fuzzy enough to frustrate foreign submariners. Oceanographic scientists and would-be mineral prospectors want as accurate and detailed mapping as they can get.

Because there has been no urgent need for offshore minerals, present and past administrations in Washington have let this issue simmer without resolution. But OTA is right. The United States should know what it has on the EEZ seabed, even if there is no immediate need for the minerals. It's time to resolve the security issue and make a focused effort to get that knowledge.

A Tuesday column. Robert C. Cowen is the Monitor's natural science editor.