Vermiculite is naturally occurring mineral that has many useful properties for applications in industry, construction and horticulture. It expands rapidly when heated and also has excellent water retention characteristics. Many misperceptions exist about the safety of vermiculite due the asbestos contamination of material produced at the Libby Mine in Montana until 1990. However, recent testing of different deposits has shown no evidence of asbestos, which points to a bright future for this versatile and valuable mineral.
Vermiculite has been a standard ingredient of soilless potting mixes for many years as it provides plants with good aeration and drainage. More recently it has been used as an additive for outdoor planting and for hydroponic growing. Vermiculite retains water very well and is both sterile and non-toxic. These attributes and its reasonable cost make vermiculite an essential product for many professional growers.
Industry has discovered a multitude of ways to use vermiculite in everything from insulating products to packaging and absorption materials. Being totally fireproof and lightweight, vermiculite is naturally suited for use as an insulation additive. It is found in masonry plaster, brake linings and fireproof doors. Vermiculite makes an excellent packaging material as it is clean, odorless and non-abrasive, and it will not rot. It is simple to use as it can be poured into shipping cartons to form a complete cushion around fragile objects such as glass and china.
Vermiculite is used as a filler ingredient and as an insulator in many construction materials. As loose fill insulation for masonry walls, vermiculite significantly improves both R-values and fire resistance. It is also added to many spray-on insulation and fire-proofing products. Vermiculite aggregate reduces the weight of concrete and allows for great versatility in the design of roof deck systems by engineers and architects. Lower concrete weight also minimizes the need for footings and structural steel which can significantly reduce building costs.
One of the strangest applications for vermiculite is as an incubating medium for turtle eggs. Biologists at Stockton College in New Jersey have had great success hatching the eggs of diamondback terrapin turtles in artificial nests made of moistened vermiculite. It's all part of a long-term project aimed at conserving this endangered species. Enamel hobbyists have found another interesting use for vermiculite. They use it to slow down the cooling process when making enamel or glass beads. This greatly reduces the amount of breakage typical when these materials cool rapidly.