du·mor·ti·er·ite (dōō-môr'tē-ə-rīt', dyōō-) n. A glassy pink, green, violet, or blue aluminum borosilicate mineral, Al8BSi3O19OH, used in spark-plug ceramics and as imitation lapis lazuli.
[French, after Eugène Dumortier, 19th-century French paleontologist.]