Findings reveal high concentrations of lithium in pyrite.

The golden glitter of a faceted nugget of pyrite has earned it the moniker "fool's gold" for its abundance, showy false promise and low value as a common sulfide – until recently. Lithium, on the other hand, has been the modern day's elusive "white gold" prize in many searches, from hard rock mines to brines and more experimental sources such as mine tailings and drill cuttings.

Recent research led by a team from West Virginia University (WVU) has now added pyrite minerals within shale to the list of possible lithium resources. This discovery promises another addition to the growing list of sustainable mining practices that do not require new mines, a bonus alternative for the otherwise involved and not-so-green processes of extracting lithium.

Lithium-ion batteries have a downside, posing a serious fire hazard due to the highly reactive nature of the mineral. (Pure lithium reacts to water, releasing heat, forming flammable hydrogen, and risking a runaway combustion reaction with others).

Primary sources for lithium, like pegmatites, geothermal and volcanic clays, are being flagged worldwide, but demand is high, and prices still aren't stable. Finding alternative stores that are local, safe, and cheap would be a boon for the U.S., which is still seeking to expand domestic critical mineral sources.

In that spirit, a research team from WVU is testing industrial byproducts like mine tailings and drill cuttings as a source of additional lithium while reducing waste.

Shailee Bhattacharya, a sedimentary geochemist and doctoral student working with Professor Shikha Sharma in the IsoBioGeM Lab at WVU, presented the team's findings this month during the European Geosciences Union (EGU) General Assembly 2024.

Alternative extraction

The WVU team found an abundance of lithium in the most innocuous of places – pyrite minerals in shale and sedimentary rock from layers of mud.

Initial findings suggest that pyrite, in conjunction with organic matter, may play a previously unrecognized role in the distribution of lithium in organic-rich shales.

It's not entirely known yet how sulfur-rich pyrite and lithium are linked, nor whether extraction would be commercially viable in practice. But it's a lucky circumstance, as lithium-sulfur batteries could one day replace lithium-ion batteries using a more environmentally friendly extraction process needing far fewer resources with less of an effect on the environment.

The study focuses on 15 sedimentary rock samples from the Appalachian basin in the U.S., where the team found an "unheard of" amount of lithium in pyrite minerals in shale, according to Bhattacharya.

Electrochemical engineers have already been looking at replacing lithium-ion with lithium-sulfur batteries, Bhattacharya said. "I am trying to understand how lithium and pyrite could be associated with one another."

Unlikely companions

It may be that organic-rich shale may show potential for higher lithium recovery as a result of this curious relationship between lithium and pyrite. However, extrapolating beyond observations of samples from the current study is not enough, Bhattacharya cautioned.

This research teases the possibility that certain shales could be a lithium source that doesn't require new mines, with the green tech industry clamoring for just such a discovery. In that respect, the researchers must expand their studies and should have plenty of support in doing so.

"We can talk about sustainable energy without using a lot of energy resources," Bhattacharya concluded.