GORNJE NEDELJICE, Serbia — Zlatko Kokanovic does not want a lithium mine in his backyard, and he will do anything he can to stop it from opening.

“All of us here, we are ready to lose our lives,” the 48-year-old farmer and father of five said. “They can shoot. That is the only way they can open the mine.”

At stake is a lush farming valley in western Serbia that holds one of Europe’s richest deposits of lithium, a precious metal that is used to make batteries for electric cars and is crucial for the global transition to green energy.

Whether there should be a mine in the valley has become one of the most contentious issues in the Balkan nation, triggering protests by thousands in a challenge to President Aleksandar Vucic.

While the government insists that the mine is an opportunity for economic development, critics say it would inflict irreparable pollution on underground water reserves, farmland and two small rivers that run through the Jadar Valley.

Thousands showed up for a major rally Saturday in the capital, Belgrade, calling for a law to ban lithium mining anywhere in Serbia.

“We are not interested in their profits,” Kokanovic said of his group, Ne Damo Jadar (We Won’t Give Up Jadar). “We were raised on this land, and we will die on this land. This land is nobody’s property, it belongs to our children.”

Exploration of the lithium and boron deposits in the Jadar Valley has been done by multinational Rio Tinto mining company for 20 years. The company has drafted plans to open a mine.

Throughout its 150-year history, Rio Tinto has faced accusations of corruption, environmental degradation and human rights abuses at its excavation sites, a history that has alarmed Jadar residents and Serbia’s environmental protection groups.

Mass protests in 2021 and 2022 forced Serbia’s government to temporarily suspend the mine plan, only to revive it in July before signing a memorandum on “critical raw materials” with the EU in the presence of German Chancellor Olaf Scholz.

Dubravka Djedovic Handanovic, Serbia’s mining and energy minister, said the Jadar Valley contains about 158 million tons of lithium, or 17% of the overall estimated reserves on the European continent.

Jadar, she said, is “one of the best explored lithium sites in Europe and probably one of the best in the world” and could “put Serbia (as) the very top country not only in Europe but also worldwide” when it comes to fighting climate change.

Djedovic Handanovic’s signature is on the EU memorandum — Serbia is a candidate for EU membership — that envisages a “strategic partnership” on sustainable raw materials, battery supply chains and electric vehicles. The plan is to not only export raw material but also boost new technologies in Serbia.

Any potential excavations will meet the highest EU standards, Handanovic said, promising “we will not do anything if that has such a negative impact that it will be detrimental.”