Tharon stone
From Tardis Wiki, the free Doctor Who reference
The Tharon stone was a type of rock native to Tharos that was used by the native inhabitants there to help channel the power of igneous rocks which the race had an affinity to. A group of Armidan came to Earth's scotland with a Tharon Stone, but were attacked by the natives. The Stone was buried underground along with healing capsules. (AUDIO Vengeance of the Stones (audio story)
