Perlite

Perlite is a sand of volcanic origin which is expanded by a high heat treatment, i.e. when it comes into contact with heat, the water it contains will evaporate and the perlite will swell like a popcorn kernel and become very light in relation to its volume. This inert material has a practically neutral PH of 7, and its composition is mainly silica, as well as alumina, iron oxide, titanium oxide, lime, magnesia, sodium oxide and potassium.

Perlite is an excellent soil conditioner and provides good soil aeration. It also provides protection against drought and excessive moisture. It can be used as an ingredient in potting soils or as a growing medium alone.