Tinclavic was a malleable mineral mined on the planet Raaga. It was primarily used by the Hakolian who used Terileptil prisoners to mine the mineral. (TV: The Visitation)
In 1984, Sir George Hutchinson had a small ball of tinclavic with which he constantly toyed during a re-enactment of the Battle of Little Hodcombe. (TV: The Awakening)
Tinclavic was also used in the construction of several spacecraft including the I's spacecraft and the Time Lords' Time Station (in which triple-bonded Polysium was also used). (PROSE: Seeing I, AUDIO: Neverland)