Mekrom

Mekrom was a planet located on the edge of known space. Geologically, it was partially composed of empathic crystal, and was once home to the native Mogor. It was later the site of a Confederation colony who called the FHD for help before they were killed by their own fear from the "ghosts" of the Mogor, when the Seventh Doctor arrived on his way to Maruthea. (COMIC: Echoes of the Mogor!)