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Webster 1913 Edition

Noun.

[Gr. [GREEK] clay +

-lite

(Min.)

Argillaceous schist or slate; clay slate. Its colors is bluish or blackish gray, sometimes greenish gray, brownish red, etc.

–

Arˊgil-lit′ic

Adj.

Noun.

Argillaceous shist or slate; clay-slate. Its usual color is bluish, greenish or blackish gray.

argillite ‎(plural argillites)

(geology) A fine-grained sedimentary rock, intermediate between shale and slate, sometimes used as a building material

a type of rock