A natural silicate ....
The distinguishing feature that differentiates perlite from other volcanic glasses is that when heated to a certain temperature, its expandability produce to increase from four to twenty times its original volume.
This expansion is due to the presence of 2% to 6% of water in the rock perlite natural state. When heated rapidly above 1000 ° C, the rock bursts as if they were popcorn as the combined water vaporizes and creates countless tiny bubbles that give the material its incredible lightness and other exceptional physical properties expanded perlite.
The expansion process also produces one of the most distinctive features of perlite: its white color. While the color of the rock in its natural state can be between a transparent light gray and a glossy black, the color of expanded perlite is between a white and a grayish white snow.
Expanded perlite can be manufactured to a minimum weight of 32kg / m3, so it is suitable for numerous applications.
Because perlite is a form of natural glass, it is classified as chemically inert and has a pH of about 7.