What does perlite mean?
Perlite is a naturally occurring volcanic glass created when water-rich lava cools very quickly. Its most familiar form is the expanded material sold for horticulture, where fine, lightweight granules are mixed into potting compost to improve aeration, drainage, and root development. In construction, expanded perlite serves as a lightweight aggregate in concrete, plaster, and insulating materials, while processed grades are also used in filtration and as fire-resistant or thermal-insulating material. The word is mainly technical but is widely understood among gardeners, builders, and materials specialists. Perlite should not be confused with vermiculite: although both are porous mineral materials used in growing media, vermiculite is a mica mineral and retains more moisture, while perlite is volcanic glass and primarily promotes drainage. Its name reflects the pearly luster that helped distinguish it from other volcanic glasses.
nounPerlite is a naturally occurring volcanic glass formed when silica-rich lava cools rapidly, typically containing enough water that it expands when heated. It is used as a lightweight aggregate in construction and insulation, and as a growing medium in horticulture.
- A naturally occurring volcanic glass used as a lightweight aggregate or insulation material.
- A granular horticultural growing medium used to improve soil aeration and drainage.
"She mixed perlite with peat and compost to improve drainage in the flowerpots."
"The contractor used expanded perlite to make the concrete lighter and easier to insulate."
"Add perlite to a heavy potting mix to help prevent waterlogging around the roots."
The plural is uncommon because perlite is normally used as a mass noun; it may be used when individual pieces or specimens are being distinguished.
"The geology reference described several perlites with different textures."
Perlite is volcanic glass with a built-in expansion trick: heat it quickly and it swells into lightweight granules, earning it a place in gardens, insulation, and construction.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does perlite come from?
The name perlite was formed in the early nineteenth century from French perle, meaning “pearl,” in reference to the mineral's pearly luster, together with the mineral-forming suffix -ite. French perle itself continues Old French perle, ultimately related to Latin perna, the source of the English cognate pearl. The suffix -ite is widely used in mineral names for substances that can occur in distinct mineral or crystalline forms.
Related word forms
How perlite is actually used
Perlite is a technical term used especially in geology, construction, and horticulture. It is usually treated as an uncountable material noun; when referring to horticultural perlite, the word commonly denotes the expanded, granular form rather than raw volcanic glass.
Easily confused with perlite
Both are lightweight mineral additives used in growing media, but perlite is a volcanic glass while vermiculite is a layered mica mineral; vermiculite generally retains more water, whereas perlite chiefly improves aeration and drainage.