Minerals Report - International Seabed Authority

tellurium and a hundred to five hundred times for molybdenum, thallium,
antimony, cobalt, manganese, bismuth, arsenic, selenium, and lead. Crusts
may have an economic potential not only for cobalt, nickel, manganese, and
platinum, but also for titanium, cerium, tellurium, thallium, zirconium, and
phosphorus.
Elements in crusts have different origins and are associated with
different crust mineral phases (67). Generally elements are associated with
five phases in crusts, δ-MnO2, iron oxyhydroxide, detrital (aluminosilicate),
CFA, and residual biogenic phases. Manganese, cobalt, nickel, cadmium, and
molybdenum are invariably associated with the δ-MnO2 phase. In addition,
in more than 40% of the regions studied, lead, vanadium, zinc, sodium,
calcium, strontium, magnesium, and titanium are also associated with that
phase. Iron and arsenic are most commonly the only elements associated with
the iron oxyhydroxide phase, although less commonly vanadium, copper,
lead, yttrium, phosphorus, chromium, beryllium, strontium, titanium, and
cerium have also been reported to be associated with that phase. The detrital
phase always includes silicon, aluminium, and potassium, and commonly also
titanium, chromium, magnesium, iron, sodium, and copper. The CFA phase
invariably includes calcium, phosphorus, and carbon dioxide, and also
commonly strontium and yttrium; molybdenum, barium, cerium, and zinc
may also be associated with the CFA phase in some regions. The residual
biogenic phase includes barium, strontium, cerium, copper, vanadium,
calcium, and magnesium, and in some regions also iron, arsenic, sodium,
molybdenum, yttrium, phosphorus, carbon dioxide, lead, titanium, and
nickel. Iron is the most widely distributed element and occurs intermixed in
the δ-MnO2 phase; is the main constituent in the iron oxyhydroxide phase;
occurs in the detrital phase in minerals such as pyroxene, amphibole, smectite,
magnetite, and spinel; and is in the residual biogenic phase. The strength of
correlations between iron and other elements depends on the relative
abundance of iron in the various phases (68). The CFA phase only occurs in
thick crusts because the inner layers of those crusts have been phosphatized.
In thin crusts or the surface scrapes of thick crusts, calcium, phosphorus, and
carbon dioxide are associated with the δ-MnO2 and/or residual biogenic
phases. CFA associated elements as well as platinum, rhodium, and iridium
generally increase with increasing crust thickness. In contrast, cobalt and
INTERNATIONAL SEABED AUTHORITY 211