Borite
Borite was a substance sometimes mined by Federation prisoners.

In 2286, after the command crew of the  unanimously decided to return to Earth to face the consequences for their illegal actions in rescuing Captain Spock, Doctor McCoy lamented to Admiral Kirk, "it's bad enough to be court martialed and spend the rest of our lives mining borite, but to go home in this Klingon flea trap..." before being cut off by Kirk. ()

Materials
Geology