Answer:
Pumice is pyroclastic igneous rock that was almost completely liquid at the moment of effusion and was so rapidly cooled that there was no time for it to crystallize. When it solidified, the vapors dissolved in it were suddenly released, the whole mass swelling up into a froth that immediately consolidated.
With time the pumice rocks undergoes with several changes including weathering, erosion, and transportation. The extent of heat and pressure, making the sediments of the pumice rocks into metamorphic rocks distinct in the chemical and physical composition of the parent material
