James R. Moffett, the executive chairman and co-founder of mining company Freeport-McMoRan, which moved from New Orleans to Phoenix after a 2007 merger, is stepping down.

The move comes as plunging commodity prices have led to mass layoffs across the entire industry and activist investor Carl Icahn recently revealed taking a large stake in the company. Icahn had pushed for cost cuts and came to an agreement with the company that put his affiliates on the board.

The company is one of the world’s biggest producers of gold and copper, both of which have tumbled in value this year, and also produces oil and natural gas.

Copper has plunged more than 26 percent as signs of a significant slowdown in China grow clearer. Oil is selling for less than half its price a year ago.

Reuters reported last week that Freeport-McMoRan is moving to sell off its oil and gas assets in 2016, including holdings in the Gulf of Mexico, the Haynesville shale formation and other natural gas assets in Louisiana. The move would end what the news service described as the company’s “ill-fated foray” into oil and gas assets in recent years.

Moffett, who goes by “Jim Bob,” will resign as chair and leave the board of directors Thursday.

He will receive $16.1 million in severance and continue to provide consulting services to the board for an annual fee of $1.5 million.

Gerald J. Ford, the company’s lead independent director, will become non-executive chairman and Richard C. Adkerson continues as president and CEO.

“During his over 50-year career in the natural resource industry, Jim Bob has become an icon as an explorationist,” Ford said.

Moffett has been Freeport McMoRan Inc.’s executive chairman since 2003 and previously served as CEO from 1995 to 2003.

A native of Louisiana who grew up in Texas, he attended the University of Texas at Austin on a football scholarship and received a master of science degree in geology from Tulane in 1963.

After working as a private independent, he formed McMoRan Oil & Gas Co. with Ken McWilliams and B.M. Rankin, deriving the company name from the beginnings of each one’s last names.

Moffett parlayed the company into one of the most successful exploration operations in the country with a 70 percent success rate in wildcatting for oil and natural gas.

In 1981, he was the chief architect of the company’s merger with Freeport Minerals Co., a name well known in Louisiana, which had its headquarters in New York. Moffett, chairman and chief executive officer of the merged company, engineered a 1985 corporate move to New Orleans.

The combined company became a major independent oil and gas producer with interests in agricultural minerals — sulphur and phosphoric acid — and in gold, copper, silver and uranium.

Freeport-McMoRan, which became known for its Grasberg copper-gold mine in Indonesia, moved its headquarters in 2007 from New Orleans to Phoenix after its $25.9 billion buyout of Phelps Dodge Corp. in Phoenix, but maintained an office in New Orleans.

Freeport-McMoRan’s most significant investment in oil and gas was the purchase of two exploration companies — McMoRan Exploration Co. in New Orleans and Plains Exploration & Production Co. in Houston — for a total $19 billion in 2013, when oil prices were twice what they are today.

Freeport-McMoRan’s oil and gas assets are currently expected to be worth about $3 billion, Reuters reported, based on conversations with individuals involved in the potential sale of those assets.

Freeport-McMoRan’s stock slid 72 cents, or nearly 10 percent, to $6.85 Monday. Its 52-week trading range is $6.08 to $23.97.