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 light weight after processing. Perlite is widly used to produce light weight wall panel due to its light weight feature. More and more wall panel facotry will adopt perlite for their final finished wall panel products. It is very necessary study perlite in more details. Perlite boulders with fireweed in foreground. Perlite softens when it reaches temperatures of 850–900 °C (1560-1650 °F). Water trapped in the structure of the material vaporises and escapes, and this causes the expansion of the material to 7–16 times its original volume. The expanded material is a brilliant white, due to the reflectivity of the trapped bubbles. Unexpanded ("raw") perlite has a bulk density around 1100 kg/m3 (1.1...