volcanictuff |
pumice |
As a noun pumice is
a light, porous type of pyroclastic igneous 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.
As a verb pumice is
to abrade or roughen with pumice.
volcanictuff |
lapilli |
As a noun lapilli is
a sphere shaped droplet of molten lava ejected from a volcanic eruption which falls to earth while still at least partially molten, ranging in size from 2 to 64 millimeters.