Perlite

Heat expanded volcanic rock is the world’s premier organic aeration and drainage agent. When the rock reaches temperatures of 850–900 °C, perlite softens (because it is a glass). Water trapped in the structure of the material vaporizes and escapes, and this causes the expansion of the material. When used as an amendment it has high permeability / low water retention and helps prevent soil compaction. Our perlite is made in Colorado.

Read more about the advantages of perlite here.