Dwarf star alloy
Dwarf star alloy was an alloy obtained from white dwarf stars. It was very expensive and very heavy. It was the only material that could hold time sensitive species. (DW: Warriors' Gate)
Usage
Rorvik's space ship was made from dwarf star alloy and required very large engines to move. (DW: Warriors' Gate)
Cadwell had a gun that could fire bits of dwarf star alloy. (PDA: Fear of the Dark)
Roz Forrester used dwarf star alloy to crush an N-Form. (NA: So Vile a Sin)
Father Kreiner had a glove made of dwarf star alloy. (EDA: Interference - Book Two)
Father of Mine was chained with a chain made from dwarf star alloy. (DW: The Family of Blood)
The United States of America military constructed a cell of Dwarf star alloy to keep The Doctor imprisoned. Once it was completed, Canton Delaware and the Doctor were able to use it's inpenetratable properties to escape through the TARDIS, which was hidden inside the cell, undetected. (DW: Day of the Moon)