• Webster's Revised Unabridged Dictionary
    • n Apophyllite (Min) 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.
    • ***
Century Dictionary and Cyclopedia
    • n apophyllite A mineral allied to the zeolites, occurring in laminated masses or in tetragonal crystals, and having a strong pearly luster on the surface of perfect cleavage, parallel to which it separates readily into thin laminæ. It exfoliates also under the blowpipe. From its peculiar luster it is sometimes called ichthyophthalmite, that is, fish-eye stone. It is a hydrated silicate of calcium and potassium, containing also some fluorin.
    • ***


Webster's Revised Unabridged Dictionary
Pref. apo-, + Gr. leaf; so called from its foliated structure or easy cleavage