What are they?

Lead is a very dense, soft, metallic element. It tarnishes rapidly in air and usually has a dull grey surface patina. Lead has been used for a wide variety of purposes since its discovery in the ancient world, including weights, plumb lines, water pipes (plumbing), stained glass window cames, roofing material, solder, pewter, shot, bullets, lead-acid batteries and radiation shielding.

Lead is also encountered as compounds in metal corrosion products (e.g. white lead carbonate), as pigments (such as red lead, chrome yellow and litharge) and as an additive to modern paints.