I'll look at mine when I'm home - I think its ceramic but I'm not certain. It is a little dark and crusty - likely from stray bits of carbon, etc. I clean it with alcohol on a swab once in a while per the instructions. As I recall, its built in a way that if a case fell through it would not cause a problem. Not sure how one would accomplish that but, since they pointed it out, it was considered in the design.