USGS Warns 2 Deep-Sea Rock Samples Caught Fire After Surfacing
Updated
Updated · ScienceAlert · Oct 12
USGS Warns 2 Deep-Sea Rock Samples Caught Fire After Surfacing
3 articles · Updated · ScienceAlert · Oct 12
Summary
Two metal-sulfide samples collected in 2022 from the Escanaba Trough spontaneously combusted in a USGS lab after freeze-drying and crushing, pushing temperatures above 100 C and fully oxidizing the rocks.
USGS researchers traced the fires to nanocrystalline marcasite—an oxygen-sensitive iron sulfide whose oxidation can trigger self-heating when samples are broken, ground or otherwise mechanically stressed.
The agency said the finding could pose a shipboard fire risk if seafloor massive sulfide mining proceeds, because rocks brought up from depth would face abrupt changes in oxygen, temperature, pressure and moisture.
Fifty-seven hydrothermal rock samples were collected from four areas in the US Exclusive Economic Zone off the Oregon-California border, where deposits contain metals such as copper, zinc and iron.
The warning lands as the International Seabed Authority has already issued exploration contracts for sulfide minerals on two deep-sea ridges, adding a new safety concern to broader environmental objections to deep-sea mining.