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No idea about the film title. But the story sounds similar to one of the legends about Guatemala's first saint, Brother Pedro or Hermano Pedro (Pedro de San José Betancur).
http://tulane.edu/liberal-arts/blogs/maxwell/hermano-pedro-02182010.cfm
Brother Pedro uses the gold lizard as security for a loan to achieve a worthy purpose, like feeding the poor or building a church, something like that.
http://www.uexpress.com/tell-me-a-story/1998/5/1/the-lizards-blessing-a-guatemalan-legend
Maybe that will help in tracking down the film?

This one was from around the mid 1970s and was a Christian short film that I was shown at school. It takes place in Mexico. The main character is a poor man who doesn't have anything going for him until he discovers a gold and jewel-encrusted salamander, which then brings nothing but goodness and wealth to his whole life. Somehow, this was supposed to be a Christian message. I may have some of the details wrong. I saw it at school when I was in the third grade. Any clues would be appreciated. Thanks.