I have an overflowing bucket of aluminum. None of it separated. I need to know how to tell the difference between cast aluminum and aluminum extrusion. For the most part I can tell what's what but there are a few things that I just don't have a clue. Things that you might think are cast but are shiny and things you would think are clean but break instead of bend. I don't want to have to go through every piece with a hammer. Is there another method to discerning the types because for me it's a $.27 difference and I don't wanna get mix prices for anything, no matter what it is, ever. I'm quite the penny pincher.