My brother gave me a 100 lbs. or so scrap lead. Some clip on wheel weights, some undetermined. When casting bullets using my Lee magnum melter (I dip), a thick "blanket" of metal comes to the surface. I appears much like Anitmony, but when I hit it with a propane torch it does not want to melt like Anitmony has for me in the past. After awhile it adhears to my RCBS ladle and turns all the colors of the rainbow...Gold, Purple, and Blue. It does not flux back into the melt with my usual mixture of powdered charcoal and parafin. I end up scraping it off the top of the melt. It is not likely zinc inasmuch as the bullets are still filled out. No mater how hot I run the pot, the bullets remain shiny instead of acquiring a frosted apearance. What have I got and what can I do about it?