The resignation is effective January 10 and Chapman will remain with the company through his departure date.
“I'm excited to be pursing the opportunity to be chief executive officer of a Mongolian-based coal producer, which has long been a goal of mine,” Chapman said.
“I firmly believe that the depth and experience of the management team leading the company, combined with the high quality coal resources, positions CERX exceptionally well to achieve its goal of becoming a leading consolidator of metallurgical coal in Colombia.”
“We are grateful to Graham for lending his tremendous talent and experience to the company as we have developed our business plans and goals here in Colombia," said chief executive Ron Stovash.
“Throughout his time with CERX, he has been instrumental in executing our business strategy.”
The company is seeking Chapman’s replacement.
Colombia Energy Resources has the largest reserve base in South America with an estimated 7 billion metric tons of recoverable reserves and 17 billion metric tons of potential reserves.
The producer changed its name from Colombia Clean Power and Fuels earlier this month to line up better with its coal market goals.
The transition to CERX on the OTC Bulletin Board was effective at the open of the market on November 4. The name change was filed on October 4 via a Schedule 14C with the Securities and Exchange Commission.