argillaceous

[ ahr-juh-ley-shuh s ]

/ ˌɑr dʒəˈleɪ ʃəs /

Geology, Petrology. of the nature of or resembling clay; clayey.

containing a considerable amount of clayey matter.

Origin of argillaceous

First recorded in 1725–35, argillaceous is from the Latin word argillāceus clayish. See argil, -aceous

Its powder is a light red, and emits an argillaceous odor when wetted.

Summary Narrative of an Exploratory Expedition to the Sources of the Mississippi River, in 1820 |Henry Rowe Schoolcraft
The solid surface of the earth is mainly composed of gravel, of calcareous, and argillaceous strata.

The World's Greatest Books - Volume 15 - Science |Various
Among the fluviatile deposits, argillaceous marl beds now play an important part.

Old Rome |Robert Burn
Here is the same induration of sandstone by means of fusion, that in the argillaceous strata has produced jasper.

Theory of the Earth, Volume 1 (of 4) |James Hutton

It is not volcanic, but consists of argillaceous schist and quartzite.

Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 6 |Various

argillaceous

/ (ˌɑːdʒɪˈleɪʃəs) /

(of sedimentary rocks and deposits) composed of very fine-grained material, such as clay, shale, etc Compare arenaceous (def. 1), rudaceous