taxite

/ˈtæksaɪt/
noun
  1. A type of volcanic rock that shows a banded or streaked appearance due to the flow of lava.
    • The museum displayed a polished slab of taxite from Mount Etna.
    • Geologists collected samples of taxite to study the volcanic eruption history.
    • The cliff face was made of taxite, with visible bands of different colors.