Five
types of mineral resource were known in the sedimentary cover of the oceans and
seas floors prior to the 1980s:
1. hydrocarbon fields including some very large zones of
oil and gas accumulation;
2.
Red Sea' type thermal oozes with increased concentrations of noble
metals;
3. ferromanganese nodules;
4. concentrations of metallic sulphides (Black
Smokers'); and
5.
cobalt-bearing ferromanganese crusts on the summits and slopes of seamounts.

Since then, the so called White Smokers', containing
sulphides of copper and zinc, have been discovered. The ore horizons (manganese,
copper, nickel and other metals) of the sedimentary cover of deep-sea basins
comprise a sixth type of mineral resource in the oceans. These horizons have not
only a theoretical, but also a principal economic
significance.