What type of rock can reach a high temprature without cracking or breaking?

I'm doing a project for science where we have to design something from our ae and convert it to something that could be made in the stone age. I'm making a type of oven
The fire will be lit by a switch that cause a flint and stone to make a spark in the oven.
We need to list what types of rocks we use and the only one i haven't got is a rock that could withstand the temprature of an oven. ((It doesn't need to be super hot just say hot enough to cook a bit of meat.

connie2012-05-26T17:51:18Z

Favorite Answer

Slate is a good rock for your purposes.

Also:

Baked clay
http://wilkinsonbaking.com/blog/96-ancient-ovens

Earth oven
http://en.wikipedia.org/wiki/Oven#Types_of_ovens