Argillite

from WordNet (r) 3.0 (2006)

argillite
    n 1: a sedimentary rock differing from shale in being bound by
         silica and from slate in having no slate cleavages

from The Collaborative International Dictionary of English v.0.48

Argillite \Ar"gil*lite\, n. [Gr. ? clay + -lite.] (Min.)
   Argillaceous schist or slate; clay slate. Its colors is
   bluish or blackish gray, sometimes greenish gray, brownish
   red, etc. -- {Ar`gil*lit"ic}, a.
   [1913 Webster]

from U.S. Gazetteer (1990)

Argillite, KY
  Zip code(s): 41121