This topic might have a better name.
We generally don't include "unnamed" in titles. I'd suggest Metal (Kaleidoscope) or Alien metal (Kaleidoscope).
Talk about it here.
The unnamed metal compound was a metal alloy not found on Earth. It was unusually dense and heavy. When in contact with human skin, the metal would transfer particles that produced a feeling of elation in the person touching it. This sensation was highly addictive.
The Rehabilitator recovered by Torchwood Three in 2008 was made of this metal. Another Rehabilitator recovered by Jack Harkness in the 1990s was presumably also made of this metal, as it came with a viewing box that allowed a user to hold the device without coming into contact with the addictive metal. (PROSE: Kaleidoscope)