Trisilicate

Trisilicate was "the hardest form of salt in the galaxy". (AUDIO: The Bride of Peladon) It was found in quantity on Peladon. Much of the technology of the Galactic Federation was based on it. (TV: The Monster of Peladon)

The negatively-charged anions of trisilicate sapped the energy of the Osirian, Sekhmet. She was entombed in a trisilicate spaceship which later crashlanded on Peladon. (AUDIO: The Bride of Peladon)

When the Federation went to war with Galaxy 5, the use and control of the trisilicate supply became vital to their war effort. The mining and refinement of the ore was threatened by a workers' rebellion against the rulers of Peladon and the Federation. The traitor Eckersley, with the help of renegade Ice Warriors, planned to ship the ore to Galaxy 5, but they were thwarted by the Third Doctor. (TV: The Monster of Peladon)

Yama-10 contained traces of trisilicate. (COMIC: Deathworld)

By 3985 the trisilicate deposits were almost totally mined out. (PROSE: Legacy)

In the 41st century, a rich and almost untapped seam of trisilicate was discovered at the site of Sekhmet's tomb. According to King Pelleas, Peladon still had "plenty to spare" if Earth's alliance with Peladon was only for the trisilicate. Arktos and Elkin sabotaged this seam in an attempt to take the trisilicate for themselves. When Elkin tried to double-cross Arktos, Arktos killed him. Before he could escape on his ship, Arktos was taken out non-lethally by Alpha Centauri. (AUDIO: The Bride of Peladon)

Behind the scenes

 * Barry Letts took the name "Trisilicate" from a list of ingredients on the back of a tube of Boots brand toothpaste.