A boron-containing mineral typically occurring as colourless glassy crystals or fine-grained masses, especially as a secondary mineral on basic igneous rocks.
Datolite is a basic calcium borosilicate, CaBSiO₄(OH). Crystal system: monoclinic.
Early 19th century. From German Datolith (formerly also written Datholit, Datholith); from dat- (in ancient Greek δατεῖσθαι to divide; from an ablaut variant (zero grade) of the same base as δῆμος) + -lith), with remodelling of the ending after -lite.