Pumice

I rub the soles of my feet with pumice in order to smooth them.

The rough pumice can abrade the skin.

Is this pumice?

Everyone is familiar with the fact that pumice floats upon water; this it does, not because it is a material specifically lighter than water, but because cavities filled with air make up a great part of its bulk. If we pulverise pumice, we find the powder sinks readily in water, but the rock in its natural condition floats for the same reason that an iron ship does—because of the air-chambers which it encloses.

Other natural products are also being used in place of plastic. They include the pit, or center, of apricot fruits and the shells of nuts. The pits and shells are ground up and are rough enough to be exfoliants. They — along with jojoba beads — have been used for years by cosmetics manufacturers. So has pumice — a lightweight stone formed by volcanic activity. It has long been used in many kinds of exfoliating and cleaning products.

This is a pumice stone.

The wind blew close to the ground - it rooted among the tussock grass - slithered along the road, so that the white pumice dust swirled in our faces - settled and sifted over us and was like a dry-skin itching for growth on our bodies.