U.S. Energy Corp. (NASDAQ: USEG) said Sept. 16 that Mark J. Larsen told the board of directors that he will retire as president and COO. He will retire Dec. 31, the company added.

Larsen joined the company in 1984 and was appointed president and COO in August 2005, U.S. Energy Corp. said. He helped transition the company to oil and gas production from mining, U.S. Energy Corp. noted.

Larsen will have an advisory role in 2015 during the Mount Emmons molybdenum project, and will remain a board member through June 2016, the company said.

"The board of directors and all members of management want to express their sincere appreciation and thanks to Mark for over 30 years of a job well done. His contribution as president and COO has helped the company expand its oil and gas interests while advancing the Mount Emmons molybdenum project,” said CEO Keith Larsen.

“We are all pleased that Mark has agreed (on a consulting basis) to continue to assist management in the marketing of Mount Emmons and advancing the plan of operation for the mine," he added, noting, "the company plans to initiate a search for a chief operating officer in the near term.”

U.S. Energy Corp., a natural resources exploration and development company, focuses on its South Texas and Williston oil and natural gas assets. It is based in Riverton, Wyo.