While Venezuela and Ecuador have alienated many energy investors by rewriting oil contracts â¿¿ increasing royalties and taxes so much that many multinationals pulled out â¿¿ Colombia's outgoing president, Alvaro Uribe, offered strong incentives.
"Colombia is one of the few countries in Latin America essentially that offers ironclad contractual guarantees over periods of 20 years," Esteruelas said.
During Uribe's eight years in office, which ended Aug. 7, Colombia's known oil reserves rose 22 percent to 1.9 billion barrels with production jumping 45 percent.
Colombia also has been the continent's No. 1 coal producer for 39 years running.
It is increasingly competing for mining investment with Peru and Chile, historically safer bets due not just to proven reserves of gold, copper and other minerals but also greater political stability.
Only about 5 million (19,000 square miles) of Colombia's 114 million hectares (440,000 square miles) have been explored, said Mario Ballesteros, the director of its Institute of Geology and Mining, though 40 percent of the country is legally off-limits due to natural reserves and environmentally sensitive regions.
Even before Uribe took office, investors considered the country's gold reserves especially promising. Colombia is Latin America's fifth-largest producer.
"It's only now that you're seeing the product of people's investigation coming through in the form of feasibility studies and project development," said William Tankard, an analyst with GMFS, a London-based precious metals consultancy firm.
Last year, Greystar Resources Ltd., a Canadian mining company, projected it could extract from the Angostura deposit in the northeastern state of Santander a total of 511,000 ounces of gold â¿¿ worth up to $611 million at today's prices â¿¿ and 2.3 million ounces of silver. In its 16 years operating in Colombia, Greystar has invested $140 million.
South African miner AngloGold Ashanti Ltd., meanwhile, has invested $159 million in Colombia since 2002 and believes it may have unearthed a monster mine, La Colosa, that could generate 800,000 ounces of gold annually, said Ivan Malaver, a company spokesman.