About Perlite

Perlite is a hydrated volcanic ore from the Pennsylvanian era of geology, with the approximate chemical composition of glass. Expansion is due to between 2-6% bound water. When heated to 1400+ degrees, the water vaporizes forcing the rock to expand. Perlite in its crude form weighs 70 pounds per cubic foot, after expansion the weight is reduced to 2-10 pounds per cubic foot depending upon the application.