Deep-sea mining operations might face a fiery and unexpected hurdle. Researchers have discovered that specific mineral-rich rocks gathered from the bottom of the ocean can heat up and burst into flames once brought to the surface and exposed to the atmosphere. A study published in Scientific Reports by scientists from the United States Geological Survey details the alarming pyrotechnic behavior of these seafloor samples, signaling a major safety concern for the nascent commercial extraction industry.
Investigators used a remotely operated vehicle to harvest 57 metal sulfide-rich rock samples from four separate regions within the Escanaba Trough. This hydrothermal zone, located along the southern Gorda Ridge off the U.S. West Coast, yields deposits rich in valuable elements like copper, zinc, and iron. During laboratory processing involving crushing and freeze-drying, two distinct samples spontaneously combusted upon air exposure. Subsequent thermal testing and chemical analysis revealed that the volatile rocks consisted primarily of nanocrystalline marcasite, an unstable form of iron sulfide prone to rapid oxidation when encountering oxygen.
The physical forces of mining, such as breaking, grinding, and crushing, coupled with ambient heat, provide enough energy to trigger this intense oxidation process. While the International Seabed Authority has already issued dozens of exploration contracts for extracting sulfide minerals along ridges like the Northern Mid-Atlantic and Southwest Indian ridges, commercial operations remain in preliminary trial phases. Experts emphasize that the stark shift in pressure, temperature, moisture, and oxygen levels between the deep ocean and the surface could force a drastic overhaul of safety protocols and regulations before any full-scale industrial extraction begins.
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