Pyroclastic rock

Pyroclastic rocks are formed from lavas which are ejected into the air, as occur in pyroclastic flows or Plinian eruptions. They include pumice, volcanic bombs, ignimbrite and ash. The airborne fragments themselves are called pyroclasts. Pyroclastic rocks differ from tephra in that the individual pyroclasts are solidified into a conglomerated rock, whereas in tephra they remain as individual particles.

The word is derived from Greek pyro meaning fire and klastos, broken; the rocks being "broken by fire".