Brazil's environment minister and a green champion has resigned after losing key battles in her efforts to protect the Amazon rain forest. MOREINFO: Marina Silva's resignation is likely to reinforce the view that President Luiz Inacio Lula da Silva is more concerned with economic development than conservation as a commodities export boom fuels Brazil's growth. It could also be a setback for Brazil's ambitions to become a major voice in global environmental debates. SCRIPT: She is known by many as the environment's guardian angel but Marina Silva has given up her ministerial fight to protect Brazil's rainforests. The champion of the green movement has quit her post as Environment Minister. She says it's become too difficult to do her job. Her decision has reinforced fears that Brazil's President is more interested in economic development than conservation. He said he regretted her decision. (SOUNDBITE) (Portuguese) BRAZILIAN PRESIDENT LUIZ INACIO LULA DA SILVA, SAYING:...