Spironium is a fictional mineral (created by DS Davidson) of great value existing in the Doctor Who continuity according to Atlantean Publishing. It is used within the TARDIS, as seen in For Want of Spironium...., with the need for it having been mentioned in the same author's The Sea Hound.
The properties, sources and general availability of Spironium have never been revealed, nor the exact use to which it is put within a TARDIS, but it is implied to be vital in maintaining smooth running of the time-ship. In For Want of Spironium... The Doctor states it is "rare and jealously guarded" on that story's world of Menhem. It is glimpsed only once, at the very end of that adventure, in the form of an exceptionally tiny yellow crystal fragment. Such a minute quantity is apparently sufficient for the Doctor's short-term needs at least.
Spironium transilicate is an alloy capable of withstanding the power of the time winds in the Vortex. It is mentioned in Child of the Vortex, as a nod towards the above.
Origin of nameEdit
If Spironium had a specific meaning, beyond being a 'scientific-sounding' word, it is long forgotten. Most likely, it would derive from the surname of its discoverer, Spiro, or because it is a spiro compound. Given its temporal energy properties, it is unlikely to be a mineral of a mundane sort.