Perlite is an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently. It is an industrial mineral and a commercial product useful for its low density after processing. It has an unusual characteristic of expanding, or "popping," up to 20 times its original volume upon being exposed to rapid, controlled heating. Rapidly heating perlite ore to temperatures of about 900°C (1,700°F) softens the volcanic glass, causing entrapped water molecules in the rock to turn to steam and expand the particles like popcorn. The resulting expanded particles—actually clusters of minute glass bubbles—are spherical in shape, usually fluffy or frothy, highly porous due to a foam-like cellular internal structure, and have a very low density.
Insulation : Perlite is used as an aggregate for lightweight, insulating concrete in roof decking, floors, decorative stone, bricks and tiles, tilt-up panels, pottery, cast sculpture, and more.
Horticultural : Perlite is widely used for roof gardens and planters, hydoponics, seed starting and plant rooting, as a soil conditioner, and to enhance the water-holding and anti-compaction properties of growing soils.
Fertilizer carrier : Perlite is used as a carrier for pesticides and herbicides, fertilizer bulking, and pelletized seeds.
Environmental Applications : Perlite is used to absorb oil, and to control and clean up pollution.