Home // Meet the Minerals // Vermiculite
Learn All About Vermiculite

Vermiculite

A mineral of many uses from fire protection to fertilizer.

What is Vermiculite?

Vermiculite deposits are associated with volcanic rocks rich in magnesium silicate minerals, and flakes range in color from black to shades of brown and yellow. It is mined as shiny flakes that resemble mica, which are heated to 900 degrees Celsius (through a process called exfoliation) causing water within the flakes to flash to steam and expand. Crude vermiculite ore is processed into particles that are eight to 20 times larger. The resulting lightweight material is chemically inert and fire resistant, with low density and low thermal conductivity. It is also odorless, has high liquid absorption capacity and catalytic properties.

Because of its lightweight, insulating, and fire- and chemical-resistant properties, vermiculite is used in construction products, such as platers and concrete, and insulation. It is also used as a primary component in coatings and as filler in inks, paints, plastics, and other materials. It’s used as an anti-caking agent in fertilizer, herbicides, and insecticides. Vermiculite improves soil aeration and moisture retention in garden and potting soils.

Fun Facts

  • The crystal structure of vermiculite contains water molecules.

Where to Find Vermiculite

Uses for Wollastonite

Agriculture & Gardening Vermiculite has many uses in agriculture, including aiding in seed germination with little water. As a soil conditioner, it helps aerate soils, providing necessary air for plants to grow in flower and garden beds and potted plants. Vermiculite is also used to help prevent the rot in stored bulbs and root crops. Vermiculite is also used as an additive in animal feed.
Construction & Building Materials Vermiculite is lightweight, fire-resistant, and insulating, making it suitable for construction and building materials, including being added to cement for roofing and flooring screeds, sound proofing, and thermal building insulation and loose-fill insulation materials in masonry work.
Fire Protection Vermiculite has high-temperature resistance – up to 1400 degrees Celsius – which imparts fire- resistant properties to fabrics, surface coatings, and building materials.
Waste Treatment The cation exchange capacity of vermiculite allows it to be used in fluid purification processes for wastewater, chemical processing, and the pollution-control of air in mines and gases in industrial processes. In addition to its ion exchange properties, exfoliated vermiculite can retain liquids within the inter-laminar voids of the individual particles, as well as between the particles themselves.
Brake Linings Given vermiculite’s thermal resistance and shape and surface characteristics, the automotive industry uses finer grades of exfoliated vermiculite for brake linings.
Swimming Pools Used as the surface below in-ground vinyl pool liners, vermiculite when mixed with Portland cement, forms a semi-hard surface that feels slightly spongy. It’s porous and won’t trap water between the floor and the liner.

Related Resources

USGS Vermiculite Mineral Commodity Summary

Keep Learning

Wait there’s more! Click below to learn about the rest of our essential minerals.

Meet the Minerals