Perlite is a volcanic glass that is often used in gardening due to its lightweight, porous nature that aids in healthy plant development. "It is made from a type of volcanic glass called obsidian," ...

Perlite, a volcanic rock, is a common ingredient in potting mixes. It improves drainage, aeration and water retention in soil. Perlite is lightweight and can be added to in-ground gardens, but it's ...