The discovery was made by chance while studying a research team’s method of leaching arsenic from a mineral called pyrite. The team found minor defects in the samples that turned out to be bubbles.

what is known

The scientists studied the nanoscale properties of the bubbles and compiled a chemical profile of the liquid. It turned out to be sea water with unique properties. The analysis confirmed that the water trapped in pyrite for 390 million years matched the chemical composition of an ancient inland sea. This reservoir stretched from present-day Michigan to Ontario. It was home to large coral reefs, truck-sized sea scorpions, trilobites, and the earliest examples of horseshoe crabs.

Eventually, the climate changed, and with that change, most living things and the sea itself disappeared, leaving only fossilized remains buried in sediments that later became the sample pyrite rock used in the experiment.

Sampling could unlock millions of years of geological record and lead to new understanding of climate change.
– says Daniel Gregory, a geologist from the University of Toronto (Canada), who was one of the leaders of the study.

Scientists describe the appearance of these particular pyrite minerals as framboids, derived from the French word for raspberry, because under a microscope they look like clusters of raspberry segments.

But it’s not all about the climate. Scientists also say research lays the foundation for new technologies to help safely harvest hydrogen or other gases underground in geological reservoirs. Until now, hydrogen has been incredibly difficult to store because it has small, light molecules. This is one of the obstacles to its widespread use as an energy source. A detailed understanding of hydrogen’s interaction with rocks may provide new solutions to this problem.