The images below are the two sides of a heavy piece of metal about 2 by 3 inches that I found on the tarmac outside a St. Albans restaurant. (Smoking does have advantages.)
Sometimes you get really lucky and see something like this. Its jewel-like qualities are obvious, but to have a "hard copy" of oil on puddle is quite remarkable. I didn't do anything to it except wash off the dirt, take the shots, and hang it on my bulletin board.