Trinitite, a type of mineral, constituted a portion of Mandalore's surface – a planet devastated by fusion bombs and fusion rays during the Night of a Thousand Tears, which glassed it. This mineral manifested as sharp, uneven peaks across the landscape, and also composed the walls of the cave that led to the Civic Center within the ruins of Sundari, a former city. The Mandalorians on the planet utilized this mineral for creating inscriptions; one such inscription was acquired by Din Djarin, who presented it as evidence of the planet's continued habitability.
The initial appearance of Trinitite occurred in "Chapter 17: The Apostate," an episode of the television series The Mandalorian. The audio description for "Chapter 18: The Mines of Mandalore" provided the first identification of the substance as trinitite. Its nomenclature is derived from trinitite, a substance found in the real world.