Quanarium was a type of alloy, one of the strongest known metals as of the 32nd century. It was also an excellent heat conductor, with a K-value of 494.
The force field generator of the prison on Radvek V was encased in quanarium alloy. In 3190, Captain Michael Burnham and Cleveland Booker were able to disable the system by heating the metal with sustained phaser beams. (DIS: "The Examples")