Perlite is used in potting mixes to enhance air circulation and alter soil structure by preventing compaction. This lightweight, white granular material resembles polystyrene but is actually expanded volcanic glass that has been heated to 1000°C, causing it to "pop" like popcorn. With a neutral pH, perlite is suitable for succulents and other plants that prefer well-draining soil. It is often compared to vermiculite, but has a different effect on soil - perlite increases drainage, while vermiculite retains moisture.