Apophyllite

(a-pof'il-lit.) [Gr. apo, from, and phyllon, a leaf.] (Min.) A zoölitic mineral with a lamellar structure, the name of which has reference to the way in which it exfoliates before the blow-pipe. It is a hydrated silicate of lime and potash, occurring in white or grayish square prisms. [s. 38]