Copper miner Freeport-McMoRan posted a better-than-expected third-quarter profit on Thursday, but said it would slow expansion plans due to inflation and slumping prices for the red metal used across the global economy.

The announcement from one of the world's largest copper producers is the latest warning from the mining industry that supplies of minerals critical to the clean energy transition are likely to fall far short of aggressive demand forecasts in coming years.

"Recent weakness in (copper) prices, combined with higher capital costs to develop new mines are making it more difficult to justify new project development, which is essential to the future," Kathleen Quirk, Freeport's president, told investors on a Thursday conference call.

Freeport's shares fell 1.3% to $35.16 in morning trading.

Copper price, which the company's stock tracks, have slipped more than 12% in the past six months. Freeport's cost to produce a pound of copper, meanwhile, rose 18% sequentially in the third quarter.

The company's earnings, for example, swing $90-million with every 10% shift in the price of diesel, a key fuel for mining trucks.

Freeport continues to struggle with attracting and training US workers, and the company's quarterly production there would have dropped without the use of copper leaching, a practice that Quirk said would increase.

Freeport posted third-quarter net income of $454-million, or 31 cents per share, compared with $404-million, or 28 cents per share, in the year-ago quarter. Excluding one-time items, Freeport earned 39 cents per share. By that measure, analysts expected earnings of 34 cents per share, according to IBES data from LSEG.

Freeport raised its forecast for 2023 copper sales volumes slightly to 4.06-billion pounds, partly due to it obtaining a crucial export license in Indonesia, where it operates the world's second-largest copper mine.