Magnificent manganese and the search for cobalt | CoG3 Consortium

At the start of a major new project involving collaboration between 8 institutions from across the UK, Rachel Norman of the Museum’s Economic and Environmental Earth Sciences division introduces us to one of the new ways the CoG3 team are unearthing cobalt, a metal of great strategic and economic importance.

On Wednesday 27 January, Museum and University of Southampton scientists searched in the Museum collections for manganese nodules.

Photo showing the specimen resting on the desk
A manganese nodule growing around a shark’s tooth. This sample was actually collected by HMS Challenger in 1875.

Manganese nodules form in very deep water on the seafloor, at the sediment-water interface, and cover vast areas. They form by the precipitation of manganese minerals out of seawater over extremely long time scales. Manganese nodules grow at a rate of just ~2 mm per million years, making them one of the slowest geological processes that we know of. This means that if a nodule reaches a radius of 50 mm, it could be 25 million years old!

Nodules usually require a nucleus to grow around, which could be a very small sedimentary fragment or something as spectacular as a shark’s tooth. The nodules are interesting to us because they contain certain metals that are of economic and technological importance, such as cobalt and the rare earth elements.

There is an increased interest in using these nodules as a resource of these metals, but in order to do so, we need to understand more about how they form, and how we can process and extract the metals of importance.

Our exploration through the Museum collections was very useful, and we found some good examples of nodules from historical expeditions that we can analyse and compare to material that has been collected more recently.

Rachel Norman

The CoG3 (Cobalt: Geology, Geometallurgy and Geomicrobiology) consortium is investigating the recovery of cobalt, a metal of great strategic and economic importance. Follow them on Twitter.