Chrondite was a mineral present in significant quantities in some asteroids. It was a dense, durable metal, especially when combined with nitrium. In 2368, an asteroid with a core of chrondite and nitrium threatened the planet Tessen III. The strong, dense core rendered the asteroid partially invulnerable to photon torpedoes, so it could only be destroyed by a concentrated particle beam. (TNG: "Cost of Living" )