Vermiculite is a mineral that is similar to mica. It is mined in South Africa, Brazil, China, the United States and Zimbabwe. Because it is a naturally occurring substance, vermiculite is safe to use in garden soil and around pets and children. Vermiculite is an important ingredient in many brands of potting soil because it helps to give it lightness and water retention capabilities.
Uses in the Garden
Vermiculite is added to potting soil to provide aeration and drainage. You can mix it with heavy clay soil to give it porosity and lighten it. The pH is neutral, so you can use it without fear of disturbing your soil's pH balance. Vermiculite also helps sandy soil retain moisture, so it's a good additive to any type of soil or potting mix.
Swimming Pool Uses
Since the 1980's, vermiculite has served a useful purpose in the construction of swimming pools with vinyl liners. When a pool is built, the walls are first positioned and then vermiculite is combined with cement and applied to the pool's floor. It has proven to be an effective and long-lasting material that helps owners avoid problems that vinyl bottom pools can cause. It costs a bit more than standard sand/cement grout mixtures, but the addition of vermiculite makes pool floors softer and stronger underneath the vinyl.
Industrial and Construction Uses
Because it is lightweight, non-toxic and fireproof, vermiculite has long been used in insulation, absorbent packing, as an aggregate in cement, a filler in plastics, in fireproof plasters and as an abrasive agent. It is also used as packaging material because it works well with corrosive or flammable chemicals and helps to prevent breakage of fragile items.
Lesser-Known Vermiculite Uses
Vermiculite is used in storm water biofilters, artificial nests for turtle eggs, as a base for charcoal, in museum exhibits, mixed with plaster to make model cars, to provide environmental control and protection at archaeological sites and as an ingredient in explosions created for films such as "Star Wars."