From the Latin argillaceus, from argilla ‘clay’, from Greek αργιλλος.
argillaceous (comparative more argillaceous, superlative most argillaceous)
- (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.