(Bloomberg) -- Talks to secure the biggest ever gold-mining deal will be extended after Newmont Corp. and Newcrest Mining Ltd. failed to reach a binding agreement in the time originally allotted.

Exclusive due-diligence rights, which expired just before midnight Thursday Sydney time, will now be extended to 11:59 p.m. on May 18, Newcrest said in a statement late Thursday.

Newmont, the world’s biggest gold miner, made a non-binding offer to acquire Newcrest for A$29.4 billion ($19.7 billion) last month, after the Melbourne-based miner rejected an earlier $17 billion offer. Newcrest, Australia’s biggest gold company, had indicated it would support the offer if it was made binding. 

Denver-based Newmont had “substantially completed due diligence,” Newcrest said in the statement, adding there was “no certainty” the process will result in a binding offer.

The deal is key to Newmont’s efforts to extend its lead over other gold mining rivals like Barrick Gold Corp. It would also increase the American miner’s exposure to copper, a key material in the clean energy transition, at a time when analysts are predicting major shortages of the wiring metal over the coming decade. Newcrest is seeking to boost its copper assets to more than 50% of revenue by the end of the decade, up from around a quarter now.

Dealmaking activity in the mining sector has ramped up in 2023, after two years of rising commodity prices left many mining companies awash with cash but short of future production.

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