Our Pizza and Baking Stones are made from a Non-Toxic Mullite mixture, containing a very high quantity of grog.
Grog is clay that has been fired to 2500 - 2600 degrees then crushed and put back into our clay mixture.
This makes our Baking Stones virtually indestructible and impervious to thermal shock.
We attacked one of our 16-inch stones with a 75,000 BTU propane burner for 20 minutes.
Looking for a little more excitement we remove the regulator, allowing a much more powerful flame. We have no idea what the BTU rating would be but it was roaring like a jet engine.
We let this go for around 15 minutes until the pipe holding the stone started to bend. We then turned off the burner to find the stone still in great working condition.