Originally Posted by Wondergirl
No, a baking stone is make of, um, stone. Here's the composition: 15-45% portland cement, 30-55% fireclay, 4-11% mullite, 2-6% silica, 0.5-3% glass fiber, 10-30% water and 0.03-1.5% of a plasticizer plus a pigment in order to produce a colored baking stone. It is breakable and must be gently washed but not with soap or SOS or Comet cleanser, just warm water and a scrubber to get off any debris.
I recently awarded my baking stone to AmVets since I hated it and never had good luck with it.