im have been looking for a type of stone to put on my hearth walls. somthing natural and cheap. im kinda a little affraid to put up shale allthought i have a ton of it for use. is there another type of cheap stone i can use to absorbe the heat when firring the stove and release it after the stove is done burning. i am using a quadrafire 2100 with a 6 inch clearance to the wall i do relize i will have to give the wall a 1 inch space behind the stone . will shale type stone explode . better ? will any type of stone explode if put behind a stove and heated to below 200 deg f.any suggestions will help.im new at this and have 4 little children so i would like it to be as safe as possible.i can not afford granite so pleas dont suggest it 4 buy 4 sheet of granite 1.5 inches thick is 1500-3600 a piece in ny