Perlite
/PER-lite/🪨 Soil Types● Basic
Also known as: expanded perlite
A naturally occurring volcanic glass that, when heated to about 900°C, pops like popcorn and expands to many times its original volume, creating lightweight white granules full of tiny air pockets. In horticulture, perlite is added to potting mixes and propagation media to improve aeration and drainage while retaining some moisture on its rough surface. It is chemically inert, sterile, and does not decompose.
Etymology
French perle (pearl) + -ite (mineral suffix)
Example
“A mix of equal parts peat, perlite, and vermiculite makes an excellent seed-starting medium.”