Freeport Chief Executive Richard Adkerson told Reuters on Thursday he has no desire to combine Freeport with Barrick – or another gold producer.

“I don’t believe it makes sense to combine a company like ours with a gold company,” Adkerson said. “But I don’t criticize Mark (Bristow) for thinking we have good assets.”

A surge in copper prices to near ten-year highs has pushed up valuations of producers of the highly conductive metal, with Freeport’s stock nearly tripling over the past 12 months.

The combination of Freeport’s improving sales and stock price has seemingly shooed away potential bidders, including Barrick, when last year, CEO Mark Bristow expressed interest in Freeport.

At the time, Barrick’s market value was twice that of Freeport. Now, given its stock surge, Freeport is worth over $18 billion more than Barrick.

Bristow has told investors his first priority now is to expand the assets Barrick already owns.