I have a fire pit in the center of my deck. Built it myself in a hurry as we needed to close when we first built the house. So no research done prior to building the fire pit.
I have fire brick on the interior and wall stone outside the fire brick. When I had my first big hot fire it cracked the mortar joints around the stone as the heat transfered from the brick to the stone. I pointed up the joints but it cracked agiain. It seems I will need either air space between the brick and stone or some type of insert.