Apophyllite
Pronunciation : A*poph"yl*lite
Part of Speech : n.
Etymology : [Pref. apo- + Gr. (Min.)
Definition : Defn: A mineral relating to the zeolites, usually occurring in square prisms or octahedrons with pearly luster on the cleavage surface. It is a hydrous silicate of calcium and potassium.
Source : Webster's Unabridged Dictionary, 1913