Why was the book the pearl banned?

What high school are you from? The Pearl is a famous short novel by John Steinbeck. Up to a point it can be examined as a sort of Male variation on the Hope Diamond legend, the curse of a valuable object. There is some violence and prejudice in the stale- the main characters are Spanish and it takes place on a Spanish-American ( either Cuba or Puerto Rico) island. In many ways it is more like Hemingway than Steinbeck and is an absorbing read. There is no dirty language, rape or seductive scenes, or anything like that. It is somewhat down-beat, but not off-color.