Perlite, a silica-containing rock, is non-toxic, inert, asbestos free and will not rot. The rock has the capability to expand up to 20 times its original size when heated.
About this Author
Jennifer Loucks has been writing since 1998. She previously worked as a technical writer for a software development company, creating software documentation, help documents and training curriculum. She now writes hobby-based articles on cooking, gardening, sewing and running. Loucks also trains for full marathons, half-marathons and shorter distance running. She holds a Bachelor of Science in animal science and business from University of Wisconsin-River Falls.