argillaceous

From Latin argillaceus, from argilla (“clay”), from Ancient Greek ἄργιλλος (árgillos, “white clay, potter's earth”), from ἀργός (argós, “white”).

• IPA^(key): /ɑːdʒɪlˈeɪʃəs/
• Rhymes: -eɪʃəs

argillaceous (comparative more argillaceous, superlative most argillaceous)

1. (chiefly geology) pertaining to clay; made of, containing, or resembling clay
   • 1864: Fitz-Hugh Ludlow in The Atlantic

     […] natural colossi from two to five hundred feet high, done in argillaceous sandstone or a singular species of conglomerate, all of which owe their existence almost entirely to the agency of wind.

   • 1994, Jeanette Winterson, Art & Lies, page 104:

     The gleam of the land is in its rocks, the fine-grained argillaceous rocks, here, not purple or grey, but green of living stone.