Trass

[træs]

解释:

(n.) 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.

整理:肯尼思

解释:

n. a volcanic earth used as a hydraulic cement.

欧文整理