Perlite is a generic name given to naturally occurring siliceous rock. Perlite is the most distinguishing feature from other volcanic glass when heated close to the softening temperature, the volume can be increased 4 to 24 times than the original volume.
This expansion is depends on crystal water in the raw perlite contains 2 to 4%. Perlite rapid evaporation of the crystal water in the structure when heated over 850 degrees explodes like corn grains and the number of pores is formed on the heat expanded perlite. This expanded perlite is an excellent thermal and sound insulating material.