Word Study
apophyllite
CIDE DICTIONARY
apophyllite, n. [Pref. apo- + Gr. leaf; so called from its foliated structure or easy cleavage.].
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. [1913 Webster]
For further exploring for "apophyllite" in Webster Dictionary Online