These are two crossword puzzles that I hand out for extra credit, one for the igneous half of the course and the other for the metamorphic half. The puzzles reinforce concepts, vocabulary, and mineral formulae that we have gone over in class and labs. The students *love* them, and usually end up working on them in groups. Both puzzles were created using the Discovery Channel Puzzlemaker: http://puzzlemaker.school.discovery.com.