Granite

Granite was a type of stone.

Peladon was rich in trisilicate (TV: The Monster of Peladon) and granite, but had no chalk. (PROSE: Legacy)

The Zeld were capable of creating flying saucers which could fly through solid granite. (PROSE: The Ghouls of Grestonspey)

Leela once referred to Aberdeen as the "granite city", and the Fourth Doctor noted that in fact the granite emitted more radiation into the bodies of the residents of Aberdeen than would a nuclear power plant into its workers. (TV: Underworld)

A granite slab was part of the invisible lift entrance to Torchwood Three. (TV: Everything Changes)