Minerals Report - International Seabed Authority

At Niau, the tonnage of material with economic merit has been
estimated to be 1 million dry tonnes with average cobalt content of 1.2%,
based on recovering only the first 2 cm of the crusts. Dilution of this layer by
the underlying material will certainly occur, but it seems possible to separate
the crust by ore processing techniques. Several similar deposits have been
discovered in the vicinity [26] that could increase this speculative inferred
resource to five Mt, which could then produce 50 000 t of cobalt.
Total resources of cobalt from Co-rich crusts in the central Pacific have
been estimated to 500 million tonnes [30] (100 deposits similar to Niau).
The exploration techniques must be improved considerably in order to
provide the necessary parameters for the design of mining and processing
methods. A better knowledge of the micro topography can be obtain by using
deep-towed multibeam sonar associated with continuous high resolution TV
recordings. Sampling methods must be completely retailored. Rotary
diamond drilling machines equipped with a multicorer system must be
developed to provide a fast and cheap sampling method with better recovery.
2.2.3. Massive sulphides deposits
Unlike polymetallic nodules and crusts, massive sulphides were
discovered rather recently. In February 1978, the French manned submersible
Cyana went to an area where it found tall conical mounds made of
scoriaceous material that was sampled. Several months later, the samples
proved to be mostly composed of zinc and copper sulphides [31]. One year
later, from the American submersible Alvin, hot springs were observed
blowing black smoke at the top of similar "chimneys". Since, many
occurrences of black smokers and massive sulphides mounds have been
discovered, not only on spreading ridges, but also in back-arc subduction
zones and the flanks of intraplate volcanoes, as predicted from fossil massive
sulphides deposits [32-34].
In spite of the considerable amount of survey work that has been done,
the available information is still inadequate to evaluate the economic potential
of these occurrences.
INTERNATIONAL SEABED AUTHORITY 431