Category:Trass

Trass, n. Etym: [d. tras or gr. trass, probably fr. It. terrazzo Terrace. See terrace.] (geol.)

Defn: a white to gray volcanic tufa, formed of decomposed trachytic Cinders; -- sometimes used as a cement. Hence, a coarse sort of Plaster or mortar, durable in water, and used to line cisterns and Other reservoirs of water. [formerly written also tarras, tarrace, Terras.]

Note: the dutch trass is made by burning and grinding a soft grayish Rock found on the lower rhine.