How can you tell if a (fake) coin is made of lead?

This is a method that often leads to disputes between appraisers at major exhibitions and owners of fake pieces who mistakenly believe they possess a treasure. After carefully examining the piece, the appraiser calmly takes a piece of paper and uses its edge to write the word "FAKE" in English! Recently, appraisal companies have reprimanded employees who engage in this practice, but some still do! The piece is from the American Numismatic Society's collection – Colorado – and is part of the tests used to determine the authenticity of pieces.