Argillaceous is a 12 letter English word. It's valid Words with friends word worth 20 points.
You can make 1417 anagrams from letters in argillaceous (aacegillorsu).
First recorded in 1725-35, argillaceous is from the Latin word argillāceus clayish. See argil, -aceous
argillaceous Rocks are rocks in which clay prevails (including shales and slates).
argillaceous rocks, composed essentially of particles of mud.
It is not volcanic, but consists of argillaceous schist and quartzite.
I also picked up a detached mass of argillaceous oxide of iron, and some fragments of striped hornstone.
The red sandstone is argillaceous, with compact white gypsum or alabaster, very beautiful.
argillaceous or marly limestone is also of common occurrence.
Its powder is a light red, and emits an argillaceous odor when wetted.
It alternates with both these rocks, and in like manner with argillaceous schist.
It must also not be full of argillaceous and iron-oxide infillings.
From clay and chalk, or argillaceous river-mud and chalk or limestone, calcined together, and then ground to powder.