The tiny rocks found with water trapped inside.
In a new study led by the Pacific Northwest National Laboratory, scientists have identified tiny bubbles of saltwater trapped in rocks dating back 390 million years. The iron pyrite rocks have been found in New York, according to a report in Science Alert. Though not the oldest water sample on record, but these are the smallest remnants of ancient oceans ever to be studied, the outlet further said. These rocks were spotted by a research team investigating toxic arsenic leaching out of rocks.
When the researchers examined the seawater trapped inside, they found it is from the time when great armoured fish, ammonoids, giant sea scorpions and trilobites roamed in the seas.
During their investigation, the researchers identified tiny defects in the form of tiny pyrite crystals, known as framboids.
"We looked at these samples through the electron microscope first, and we saw these kind of mini bubbles or mini features within the framboid and wondered what they were," Geochemist Sandra Taylor, from the US Department of Energy Pacific Northwest National Laboratory (PNNL) in Washington State, said about the discovery.
She added that this study could provide scientists the knowledge on how to safely store hydrogen fuel or other explosive gases underground or in rocks.
"This work shows the existence of tiny defects in minerals at the nanometre scale. We see that they can trap water and in turn it's likely that they could trap hydrogen as well. So with all the effort going into understanding the storage of hydrogen underground, it is important to consider what role these defects may have and we think we can apply this approach to do that," added Ms Taylor.
The trapped water will also give an insight into the climate of ancient Earth and how it changed over time.
The findings were published in the journal Earth and Planetary Science Letters on November 17.