[signguy]

if you ever want to know how a certain stone will react to fire put it in the fire . I had to build a fire pit out of a certain stone I had never used before . So i took three pieces home and tested there properties with fire, One i placed on the edge of the fire pit(copping) and one in the center and one close to the centre(so I could remove it during the burn.I then built an average fire,once it got good and hot i removed one stone from the center and let it cool quickly ( becareful rocks can actually explode with drastic temp. change) let the rest of the rocks cool naturally and check for crackes or even tap lightly with hammer to se if the stone has lost it's integradey. this may seem like a lot of work but you can do this with several types of stone at once and record your findings for future fire pits....