ignimbrites

Noun

ignimbrite (countable and uncountable, plural ignimbrites)

1. A deposit left by a pyroclastic flow from a volcano, consisting of ash, pumice lapilli, and lithic fragments.
   • The walls of the houses and shops and temples were often constructed of alternating courses of large blocks of ignimbrite and small, sienna-coloured Roman bricks.2004, Richard Fortey, The Earth, Folio Society, published 2011, page 13