Deep-sea mining faces surprise risk of rocks catching fire

AI desk brief

USGS researchers found that some metal-rich deep-sea rocks from the Escanaba Trough can spontaneously ignite when exposed to air and processed, with two of 57 samples generating temperatures above 100°C and fully oxidizing in lab tests. The likely trigger was nanocrystalline marcasite, an unstable iron sulfide, raising fresh handling, transport and vessel-fire concerns for any future seabed mining operations.

The finding matters for prospective deep-sea sulfide projects because these deposits can contain copper, zinc, gold and silver, but their behaviour after recovery remains poorly understood. The study suggests operators may need to test mineral stability and develop new procedures before commercial extraction can scale, adding another hurdle to an industry already facing regulatory and environmental scrutiny.