I have this old gasser that serves as a grill, a warming oven, and a baking oven from time to time.
I got a piece of granite that was scrap from a kitchen countertop and I put it on the top deck of the grill. My thoughts were that it would soak up a lot of heat and be very slow to cool down when the top was opened. It heats up and stays hot for a long time.
It is thick and weighs about 15 to 20 lbs.
I usually use it to place things like grilled veggies after they are cooked to hold while I cook more. Sometimes there is not enough space on the grill to cook everything at once. I recently discovered it also beams heat onto the top side of things cooking on the main grill.
Last Christmas morning, we wanted biscuits with breakfast, but the ham was occupying the oven inside. It was about 20 degrees outside. With nothing to lose, I lit off the grill and let it heat for about a half hour. I sprayed the top of the stone with Pam and wiped it off, the placed the frozen biscuits on it. I checked back about 30 minutes later and they were perfect. Browned just right. We had the best tasting biscuits I had ever eaten that morning.