Paxltt
From Tardis Wiki, the free Doctor Who reference
Paxltt was a mineral unique to the planet inhabited by the Tryods and another humanoid species. The Second Doctor identified it as a mineral unique to the planet after Asiries gave him a lump of it, promising never to throw it at the Tryods again. (PROSE: The Word of Asiries [+]Loading...["The Word of Asiries (short story)"])