Datolite n. : A borosilicate of lime commonly occuring in glassy,, greenish crystals.

Example:


Taxonomy
Datolite, free encyclopedia, minerals, type localities, native copper, copper deposits, search, prismatic crystals, nodular, masses, luster, vitreous, light green, the Connecticut River, Arendal, Aust-Agder, zeolites, of the Lake.

Defination from the web:
Datolite crystallizes in the monoclinic system forming prismatic crystals and nodular masses. The luster is ... Unlike most localities throughout the world, the occurrence of datolite in the Lake Superior region is usually fine grained in texture and possesses colored banding. ...