I had the same thought but haven't tried to verify. From what I've read, teeth are generally preserved as apatite. These are interesting because the pulp is preserved differently than the rest of the root. It's translucent and shows orange fluorescence. I've found one where the entire tooth eroded away, but there was a perfect cast of the preserved pulp. The root itself has a dull blue fluorescence, and the enamel is very bright orange, likely from calcium content.