The nugget in this shot looks like black and brown cauliflower. Indeed, there is an important deep-sea resource of minerals behind the exotic tuber.
They are black-brown, spherical or cauliflower-shaped, growing as if in slow motion and often only a few centimeters in length: manganese nodules. It is located in ocean depths of at least 4000 meters and covers the sea floor in huge quantities. The largest deposits of manganese nodules are loosely located at the bottom of the Pacific Ocean. Tens of thousands of tons of tubers have already been discovered in one Central Pacific region alone.
Although the black nodules look strange, like the white sponge inhabited deep-sea specimen in our photo, they may become important: Manganese nodules are promising sources of manganese as well as copper, nickel, cobalt, zinc, and other minerals.
These ore blocks could arise because minerals dissolved in seawater have accumulated micrometer-sized bacteria over millions of years. The microorganism acts as a crystallizing nucleus, enhancing the continual attachment of new metal ions to the protein layer on its outer wall. Over time, new metallic layers are created.
Precious minerals come from manganese nodules from sea sediments and also directly from underground rocks. Due to the ocean’s widespread circulation, the water penetrates the porous rocks below the sediments, so that heat and chemical components are drawn from the ocean floor. Minerals seep into the ocean floor, near-land waters, and deep-sea nodules on the ocean floor.
As a natural resource for the minerals, manganese nodules raise desires: In areas with high deposits of raw materials – such as the Clarion-Clipperton Fracture Zone, which extends from Mexico to Hawaii – Germany has, among other things, secured deep licensing zones. – offshore mining of ore blocks. But mining deep in the ocean is very costly and environmentally harmful. Harvesting manganese nodules with the help of remote controlled collection machines excites sediments, causes noise and disturbance, destroys and changes the delicate environment of animals for decades.
German scientists have been researching the potential consequences of deep-sea mining in the Clarion-Clipperton region in the Pacific for a long time. As part of the MiningImpact project, they are now embarking on an expedition to assess the impacts of aggregate compounds and find mining methods that reduce damage to the deep-sea ecosystem.