Lead
Lead
A fairly common metal found on Earth and possessing qualities of extreme density and softness. Lead is toxic to humans in small amounts and its use is now more restricted, but it remains valuable for screening radiation and is still important in many industrial metal alloys and some paints.
Perhaps no metal on Earth is as important in Superman's career as lead. It protects him from the harmful radiation of Kryptonite, but at the same time, blocks all of his extra vision powers, including being resistant to heat vision.
Many criminals protect their lairs and vehicles with lead to avoid Superman's detection. For example, Lex Luthor creates laboratory hideouts that are lined with lead to conceal them from Superman's X-ray vision, see Luthor's Lair, Luthor's Lair II, and Luthor's Lair No. 5.
Both the Anti-Superman and Anti-Batman use lead-lined masks to prevent Superman from discovering their real identities with his X-ray vision (WF No. 159/1, Aug 1966: "The Cape and Cowl Crooks!").
Superman dons a lead suit to ward off the effects of a Green Kryptonite sword and a Red Kryptonite spear brandished by a "super Perry White" under the influence of a plant intelligence (Act No. 278, Jul 1961: "The Super Powers of Perry White!").
Achilles has the lead box covering his foot housing "a powerful anti-magnet device" capable of repelling "all metal objects," thereby rendering Achilles invulnerable to all metal weapons (S No. 148, Oct 1961: "The 20th Century Achilles!").
Superboy wears lead goggles to block his ability to read a playing card in a gambit for his foster-parent's life (SB No. 148, Jun 1968: "Superboy's Greatest Gamble!"). In his battle with the giant ape Titano, Lois Lane uses Titano's tendency to imitate the actions of others to get the ape to wear a pair of giant spectacles that Superman had constructed and treated with a lead coating to blocked Titano's Kryptonite-vision and thus inable Superman to defeat the great beast (S No. 127/3, Feb 1959: "Titano the Super-Ape").
Lead must be abundent on Krypton, because when Argo City is blown into space during the planet's destruction, the residents pave the ground with lead to protect them against Kryptonite (later accounts say Anti-Kryptonite) radiation (Act No. 252, May 1959: "The Supergirl from Krypton!").
Lead is extremely harmful to Daxamites, weakening them and shortening thir lives (SB No. 89, Jun 1961: "Superboy's Big Brother!"; "The Secret of Mon-El!"). As a result, Mon-El moves to the Phantom Zone until a temporary remedy devised by Saturn Girl enables him to join the Legion of Super-Heroes (Adv No. 300, Sep 1962: "The Face Behind the Lead Mask!"). Later, Brainiac 5 invents an improvement, and makes a serum that Mon-El takes every 48 hours and gives him more permanent protection against lead (Adv No. 316, Jan 1964: "Origins and Powers of the Legion of Super-Heroes!").
Ultra Boy, a member of the Legion of Super-Heroes, Penetra-Vision is more powerful than Superboy's and Mon-El's, since unlike their own "super" Vison, Ultra Boy's can see through everything, inlcuding lead.