Gold

Gold was a chemical element much prized by humans, and a major weakness of Cybermen. Gold had several isotopes. Gold-197 was very stable. Gold-198 had a half-life of three days, and Gold-194 had a half-life of one and a half days. (PROSE: Midnight in the Café of the Black Madonna)

According to the Tenth Doctor, gold was non-corrosive, malleable and ductile. (TV: Planet of the Dead)

As it was prized by humans; it was an item that could be invested in. During a huge market collapse during Miracle Day, the best advice the people were given was to invest in gold. (TV: End of the Road) "Worth your weight in gold" was an Earth compliment. (TV: Rendition)

The Animus could control beings that were in contact with gold, which led to it controlling the Zarbi. (TV: The Web Planet) The Keratin could similarly use gold to conduct and amplify their psychic powers. (AUDIO: The Glittering Storm)

Nero gave Barbara Wright a gold bracelet. (TV: The Romans) The Animus was able to control her through the bracelet. In addition, Ian Chesterton owned a gold pen which disappeared when he went onto the surface of Vortis and took it out. (TV: The Web Planet)

Gold was used to power the teleportation devices of the Linktons, which allowed them to travel vast, inter-galactic distances. (PROSE: The Living Wax)

The Seventh Doctor kept some Warlock in a gold snuff box. (PROSE: Warchild)

Lady Peinforte dipped her gold-headed arrows in poison as her "calling card". (TV: Silver Nemesis)

Flidor was rich in blue-veined gold, (The Dalek Book) which was used to construct the Dalek Emperor's casing. (COMIC: Genesis of Evil)

Prospecters flocked to Mal Oreille, mistakenly believing its yellow-algae infested seas to be rich in gold deposits. (PROSE: Biology Lesson on Mal Oreille)

In payment for his service, offered Chang Lee two bags of gold dust that was kept within the Doctor's TARDIS. The Master claimed the dust, along with the TARDIS, had been once his before the Doctor stole it. After the Eighth Doctor defeated the Master, he let Lee take the gold dust. (TV: Doctor Who)

Using gold as currency fell out of favour in the late 21st century. (AUDIO: The Evil One)

Owing to its non-corrosive nature, gold essentially choked the Cybermen's respiratory systems. The glittergun, a weapon used during the Cyber-Wars, fired gold dust at its targets to exploit this weakness. Adric's badge was gold-edged, allowing for the Doctor to grind it into the Cyber Leader's chest and asphyxiate him. (TV: Earthshock) Gold appeared to affect some varieties of Cybermen in the way that silver affected werewolves, so that gold coins or gold-tipped arrows fired at them had the same effect. (TV: Silver Nemesis)

During a time period in which the Cybermen had been reduced to small remnant groups wandering around the galaxy, one group tried to take revenge by making a desperate attempt to blow up the remnants of the planet Voga, a planetoid of pure gold that had wandered into the solar system and had become a moon of Jupiter. They hoped that this would disrupt their enemy's supply of the element. (TV: Revenge of the Cybermen)

Sometimes gold was the element used to construct golden casings for Gold Daleks and Supreme Daleks. (TV: Day of the Daleks, Frontier in Space)

In order to repair the circuitry of a spaceship that crashed in Nottingham in the late 12th century, the Sheriff of Nottingham forcibly collected gold from the local population and had it melted down. Imitating a move the Twelfth Doctor earlier performed on him, Robin Hood pushed the Sheriff into a vat of molten gold, killing him. When the ship launched, the Doctor realised that it didn't have enough gold content to reach orbit and would explode and destroy half the country. To prevent this, the Doctor, Robin Hood and Clara Oswald worked together to fire a golden arrow won in an earlier archery contest into the ship's engine, giving it enough of a boost to reach orbit where it exploded harmlessly. (TV: Robot of Sherwood)