Table of Contents
In the Area there are three main types of ore deposits, namely:
- Polymetallic nodules,
- Polymetallic sulphides,
- Cobalt-rich ferromanganese crusts.
Polymetallic nodules
These nodules, also known as manganese nodules, are found in lakes, shallow waters and on the ocean floor, in places with extremely low sedimentation rates. They consist mainly of iron and manganese silicates and hydroxides, but also contain small amounts of nickel, copper and cobalt.
The richest deposits are located in the Clarion-Clipperton Fracture Zone (west of Mexico), in the Central Indian Ocean Basin and the Basin of Peru. Polymetallic nodules grow extremely slowly, with a rate of up to 10 mm per million years.
Polymetallic sulphides
These deposits of sulphurous minerals of hydrothermal origin occur in two forms, namely as hydrothermal vents, whether or not extinguished, or as submarine massive sulphide deposits in the vicinity of these hydrothermal vents. They consist mainly of copper and zinc ores, but also contain lead, gold and silver.
Cobalt-rich ferromanganese crusts
These deposits, also known as manganese crusts, occur in waters between 400 m and 5,000 m in areas with a large volcanic activity, where the flow is too strong for the deposition of loose sediments. They are formed by precipitating metals from seawater on a hard surface and, in general, have a composition that is comparable to polymetallic nodules. However, they contain higher concentrations of cobalt, platinum and rare earth elements.
More information
International Seabed Authority (2002). Polymetallic massive sulphides and cobalt-rich ferromanganese crusts: status and prospects. Technical Study: No. 2. ISBN 976-610-467-0
International Seabed Authority (2010). A Geological Model of Polymetallic Nodule Deposits in the Clarion-Clipperton Fracture Zone and Prospector’s Guide for Polymetallic Nodule Deposits in the Clarion Clipperton Fracture Zone. Technical Study: No. 6. ISBN 978-976-95268-2-2.
