Deep-sea mineral samples spontaneously ignite in laboratory tests

Researchers studying deep-sea minerals have discovered that certain sulfide-rich rocks can spontaneously ignite when exposed to air. During laboratory analysis of 57 samples collected from the Escanaba Trough in the Pacific Ocean, two samples caught fire after undergoing freeze-drying and crushing processes.

The reaction caused temperatures to exceed 100 degrees Celsius, leading to the oxidation of the materials. Scientists identified the presence of nanocrystalline marcasite, an iron sulfide mineral, as the primary cause. When marcasite reacts with oxygen, it releases heat that can accumulate and trigger combustion under specific conditions.

This finding, published in Scientific Reports, highlights potential fire hazards for vessels and facilities involved in deep-sea mining. The research was conducted by the United States Geological Survey (USGS) in collaboration with the Bureau of Ocean Energy Management (BOEM) and the National Oceanic and Atmospheric Administration (NOAA).