Mining the Deep Sea: what’s it worth?

a fragment of a hydrothermal vent

The shimmering insides of a vent chimney

In Jules Verne’s 20,000 Leagues Under the Sea*, the iconic Captain Nemo announced that “in the depths of the ocean, there are mines of zinc, iron, silver and gold that would be quite easy to exploit” while predicting that the abundance of marine resources could satisfy human need. If the pace of development for deep-sea mining projects and the estimated value of deep-sea ores is any indicator, it seems as though our misanthropic mariner was wrong on both counts.

In The abundance of seafloor massive sulfide deposits, an international team of geologists attempts to quantify the total available copper and zinc contained in deep-sea massive sulfide mounds. Seafloor massive sulfide mounds are a byproduct of the processes that create deep-sea hydrothermal vents. As super-heated sea water emerges from the vent, it deposits heavy metals and other elements and minerals along the walls of the vent. Over thousands of years, an active vent field can build up a huge mound of metal and mineral rich ore – a massive sulfide mound. In addition to copper and zinc, these mounds can contain gold and silver. Generally, the ore is of much higher quality than its terrestrial counterpart. Over the last few decades, many exploration companies were eyeing these deposits, but it’s only recently that technological developments and economic incentives have aligned to permit potentially profitable deep-sea mining.

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