New Oven- Base Plans

[npolce]

Hello, I am new to this forum but in the middle of a build. My oven will be 48" circular oven but the base of the oven is my problem. My wife does not like the traditional Block base construction and would like to build it on Granite Posts. The full hearth base will be suspended on these 4 posts on each of the corners it will hold a 6' x 7' hearth by 6"Thick. I am concerned with the span of this slab and its ability to hold, what I estimate is about 1500lbs without collapsing. There will be no middle support just the 4 piers in the ground. I have concreted these posts in the ground using SonoTubes at 3' Depth now I need to build the forms for the hearth. I know that I will be using 1/2 re-bar for slab support grid but not sure if I should be worried about its ability to hold this much weight. Does anyone have any ideas or information? There are no examples on the internet for such a design, So either I am breaking new ground or its just a ridiculous idea!!! Any info or direction will be appreciated