Thanks for all the comments on my point. Sonny, I,m quessing that it,s glass but it,s good glass not my usual factory slag finds. Orgin is a little mystery, a friend of mine who lives in Sheffield , Pa. had four or five of these big nodules laying around outside of his house. He said they were there when he bought the place, anyway he sells place an took glass with him an gave me one of the big nodules pictured. Rick thanks but sometimes I don,t think I,m improving very fast. Pat B. took my glove off after percussion an about the second pressure flake went in to my finger yoooooow, ya its sharp. Dmann, wished I could help ya but I end up buying most of my rock at knapins or trade goods for rock or as this glass, friend gave to me. NW Penna. is rock poor. Thanks guys for looking. Later Bob