What is a polymetallic nodule?

The polymetallic nodule is a mineral concretion between 5 and 10 cm in diameter found on abyssal plains.  

It is formed in concentric layers around a core like a shark's tooth, by the precipitation in seawater of metals such as manganese and iron, as well as copper and nickel. 

The nodule is the result of a very slow geological phenomenon, growing by only a few millimetres every ten thousand years. Some are several million years old!

The discovery of these nodules in the oceans dates back to the Challenger expedition between 1872 and 1876. Almost 100 years later, John Mero, an American geologist, described in 1960 the potential of these nodules to cover some of our mineral needs.  

These nodules are currently the object of covetousness on the part of certain States or private companies who are considering collecting them from the seabed to meet the needs of new technologies in the context of the energy transition.

In the North Pacific alone, the Clarion-Clipperton zone, which covers 9 million km², could contain up to 34 billion tonnes of nodules, including around 340 million tonnes of nickel and 275 million tonnes of copper.  

Since 1994, the International Seabed Authority (ISA) has regulated the exploration and exploitation of deep-sea mineral resources located in "the Area", which has the status of "common heritage of mankind".  
 

Photo : Ifremer