Out here in the desert we hit alot of hot rocks, usually iron, sometimes magnetite, when we are nuggetshooting. The big magnetite one I found was laying on a dirt road and I noticed a weird rock as I was walking my dog. They are always worth taking a look at before assuming its just another hot rock. I try to take a look and see if its unusal before throwing a hot rock aside. What is interesting, is iron or magnetite rocks usually occur in areas with high minerlization, often occuring in gold bearing areas. Maybe your backyard holds some other treasure! Worth investigating maybe....Yep, I filed it, steel looking, bummer.