°A light, porous type of pyroclasticigneous rock, formed during explosive volcanic eruptions when liquid lava is ejected into the air as a froth containing masses of gas bubbles. As the lava solidifies, the bubbles are frozen into the rock.
°A light, porous type of pyroclasticigneous rock, formed during explosive volcanic eruptions when liquid lava is ejected into the air as a froth containing masses of gas bubbles. As the lava solidifies, the bubbles are frozen into the rock.