pumice stone is floating on the water. pumice has an average porosity of 90%, and initially floats on water. pumice varies in den

backdrop black bright brown bubble care clay color coral craters exfoliation experiment float foamy hole laboratory lava light lightweight liquid magma mineral pattern plaster pore pores porosity porous pumice pumicite purity refreshing rehabilitation ripple rock rough sand sandstone sandy scrub spa splash sponge stone test vitality volcanic volcano water white