To tell the truth I'm not sure what it is. I got it from work when it was in the trash. I used it for a lot of things. I have some I use for cutting boards, and hammer and tooling stamps. I have some stamps I've made that are 5/16 around and I can pound on them all day long and nothing hurts it. When I use it as a cutting board it's so hard that some times I could swear it dulls my knife. I used my maul to pound and Osbourn 1/8 thonging chisel thru three layers of what had been 13 oz veg tanned leather that I skived down to 8 to 6 oz and it didn't even skuff it.