Perlite is a volcanic debris encountered the acidic lava lakes, marine after a sharp cooling after a vitrified form of volcanic rock, which formed in the late Jurassic to the Cretaceous period, which is some 100 million 5 3 1000 millions of years. According to the internal crystalline water content in different areas into obsidian, perlite Perlite is to smash the magmatic rocks heated to 1000 ?C to form the above expansion, with a closed porous structure, Particle diameter is generally 0.5 ~ 2.5mm between. Light, good ventilation, no nutritional elements. Easy to use in the mixed culture floating on the surface of soil