||Raise the Titanic!
||Byzanium is a fictional element within the book Raise the Titanic! and its film adaptation, which serves as a main focus of the story arc. It is a powerful radioactive material sought after by both the Americans and Russians for use as either an energy source for a missile defense system or atomic super bomb. The largest known natural source of Byzanium was on the island of Novaya Zemlya, which was mined in the early 20th Century and supposedly taken aboard the ill fated RMS Titanic during her first and only voyage.
|Cobalt Thorium G
||Dr. Strangelove, Big Guy and Rusty the Boy Robot
||In Dr. Strangelove it is an element used in the Russians' doomsday device. Both (real) elements Cobalt and Thorium can be used in atomic weapons to increase the amount of dangerous nuclear fallout, which agrees with the sense in which "Cobalt Thorium G" is used in the movie.
In the "Wages of Fire" episode of Big Guy and Rusty the Boy Robot, it is revealed that the BGY-11 is powered by a Cobalt Thorium G power core.
||The Terro-Human Future History, The Collapsium
||Collapsium was first mentioned by H. Beam Piper in his Terro-Human Future History series. Piper describes it as "the electron shells of the atoms collapsed upon the nuclei, the atoms in actual contact." Collapsium can only be worked by abrasion with cosmic rays. It is resistant to both ordinary matter projectiles and all forms of radiation, and can be plated on to ordinary steel to form a protective layer. The main use for collapsium is as armor for spacecraft.
A different version of collapsium appeared in Wil McCarthy's novel The Collapsium. McCarthy's collapsium is composed of black holes and can be used to warp space and time in accordance with the wishes of its inventor.
||A crystalline material, originally in various colors with separate effects, harmful to Kryptonians and created during the destruction of Superman's home planet Krypton; synthesis is also possible. John Byrne's retcon of the DC Comics universe established green kryptonite as a compound and later issues had experiments by Batman and Luthor reestablish the Pre-Crisis versions of red, blue, and gold. Kryptonite has been found in the real world (according to its chemical composition) and has none of the properties or color variations of fictional kryptonite. However, DC Comics had previously described kryptonite as an alien element with a higher atomic number than known Earth elements.
||Middle-earth, Dungeons & Dragons,The Elder Scrolls IV: Oblivion, RuneScape, Golden Sun, Terraria, World of Warcraft, Clash of Kingdoms, MapleStory, Guild Wars 2
||Originally described in J.R.R. Tolkien's Lord of the Rings trilogy, mithril is a durable silvery metal that is very light and extremely strong. Mithril means "grey gleam", but is translated as "true silver". It was mined in native form in Moria. It can also be worked into other forms with unusual properties such as reflecting only the light of the Moon.The fictional metal has expanded to be included in various other fantasy universes, games, and books. "Mythril" appears in the video game series Final Fantasy. Also, "Mithral" is used in D&D books and "Milrith" in Simon the Sorcerer. In the Warhammer world, the High Elven metal "Ithilmar" has similar properties and usage. In RuneScape it is a lightweight blue metal stronger than steel. In World of Warcraft, Mithril is a silvery-white mid level mineral, that can be mined as an ore and smelted into a bar using the mining profession. "Mithral" is also featured in the Dungeon Master series. It appears in armor form in The Elder Scrolls IV: Oblivion. It also appears as a cyan metal used to make armor and weapons in MapleStory.
||A strange, iridescent metal that is highly valued. It radiates dangerous amounts of raw enchantment and is so unstable it can only exist in a universe saturated with raw magic.
||Mythology (Atlantis), Fate of Atlantis, Shadowrun, Earthdawn, Exalted, Irregular Webcomic!, Star Ocean, Final Fantasy (various), Poseidon: Master of Atlantis, Age of Mythology: The Titans, The Elder Scrolls V: Skyrim, MapleStory, Dragon Quest Heroes: Rocket Slime, Guild Wars 2, Terraria, Kingdom Hearts
||A metallic pink or red colored metal mined in Atlantis; another name for it is mountain copper. May be based on Auricupride. Used to power machinery in Atlantis in the Indiana Jones adventure game. In the Exalted setting Orichalcum is the strongest of the five magical materials and can be made by distilling ordinary gold using Gaia's blood (Magma) and concentrating sunlight using large occult mirrors. Found in Final Fantasy as a rare material with varying properties. In the Soul Calibur series, Sophitia has a sword and shield set named Orichalcum. Used in smithing to craft Orcish weapons and armor in The Elder Scrolls V: Skyrim. In Maplestory it is a fuchsia metal used to craft armors and items. In Shadowrun, orichalcum is a magical alloy of gold, silver, mercury, and copper. Also named "Orichalcon" in some games.
||A metallic, radioactive, explosive element found in some planetary cores that is mined and refined to become the main fuel for starship sub-light engines in the OtherSpace multiverse, as well as a potent explosive. Never to be mistaken for Molybdenum.
||The Invisible Ray
||Radium X was an intensively radioactive extraterrestrial element discovered by Dr. Janos Rukh (Boris Karloff) in the 1936 film the The Invisible Ray. In the film, Dr. Rukh creates a death beam projector which harnesses the incredible power of Radium X for use as a destructive weapon of mass terror. Interestingly, Radium X also had healing powers. In a memorable scene, Rukh restores the sight of his blind mother (Violet Kemble Cooper) with the Radium X projector after developing a filter to curb its destructive effects. According to legend, this scene inspired John Lawrence (the younger brother of physicist Ernest Lawrence) to use radiation on his mother—who had been diagnosed with inoperable cancer of the uterus. Not to be confused of the real life Radium.
||Teenage Mutant Ninja Turtles
||Used by gym owner Wally Airhead and his men in the episode "Leonardo Cuts Loose". Provides the user with strength. Not to be confused with real element Strontium, which has a radioactive isotope called Strontium-90.
||Bertil Mårtensson's Jungfrulig planet
||A superheavy element, number 183, stable, "eerily unscientific properties". Necessary for protecting the crew of faster-than-light spaceships from high-energy graviton radiation associated with powering up (or powering down) the engines.
||Stardust series, Liaden universe, Rise of Nations: Rise of Legends
||In the Liaden universe, the planet Surebleak
was at one time a mining center for timonium before large amounts were discovered in another nearby star system. Timonium is a radioactive element used as an internal powersource for high tech devices.|
||Aerospace term 
||A substance having the exact properties required for a piece of hardware or other item of use, but not obtainable either because it theoretically cannot exist, geopolitical events preclude access to it, or because current technological limitations prevent its manufacture.
||Aerospace term 
||An alternative to unobtainium, possibly indicating that the substance in question is theoretically impossible according to known scientific theory. Historically Scramjets have been described as being made from unobtainium reinforced wishalloy.
||The Chase of the Golden Meteor
||An element which is, in the French first edition of the novel, about a hundred thousand times more radioactive than radium. In the English first edition this has been reduced to a hundred times. Xirdalium was invented by Jules Verne's son Michel, who introduced it to the novel, together with the character Zephyrin Xirdal, a 'private genius' who synthesized the new element. In the story Xirdal then uses Xirdalium in a contraption emitting a strong tractor beam able to alter the trajectory of the meteor mentioned in the novel's title.
||A bright green mineral used to produce incredibly strong alloys originally discovered by explorers from the Neutral Territories. References to it are found throughout the game's item descriptions and is used in everything from spaceship hulls to railgun ammunition. Ore containing Xithricite can be mined from asteroids by players.
||According to the book, one second of direct exposure is equivalent to a lethal dose, with a reading of 3217.89 Rads/hr from 15 metres away. The blade of St. Michael's sword was forged from it.
||80Ir does not exist; the lightest known isotope is 164Ir.
||The Gods Themselves
||An isotope of plutonium which is too unstable to exist in our universe but which exists naturally in fictional parallel universes whose strong nuclear forces are more intense. This is utilised as a source of energy where it is turned into 186W, releasing electrons in the process.
||The description of this isotope is entirely correct; the lightest known isotope of plutonium is 228Pu.
||any element, but most commonly potassium
||This rare and expensive substance used in jumpgates is formed when ordinary matter is subjected to the stresses of a supernova, pushing some of its electron pair-bonds into hyperspace. The most commonly found form is derived from 40K, giving quantium-40. The name was coined by David Strauss in response to a request from the show's creator.
||40K is a naturally occurring isotope of potassium which is used to date rocks. However, the method of obtaining quantium as described has not been demonstrated in real life.