Perlite is a naturally occurring volcanic glass that expands significantly when heated. It is an amorphous mineral consisting of silicon dioxide (SiO2) and water. The expansion occurs due to the presence of water in its structure, which vaporizes and creates numerous tiny bubbles, resulting in a lightweight material with excellent insulation properties.

Here are some key points about perlite:

1. Formation and Composition:
   • Perlite is formed when obsidian, a type of volcanic glass, comes into contact with water. This interaction causes the obsidian to hydrate, leading to the formation of perlite.
   • The mineral is composed mainly of silicon dioxide, typically around 70-75%, along with water content that can range from 2 to 5%.
2. Physical Characteristics:
   • Perlite is characterized by its perlite lightweight nature, low density, and high water content.
   • The mineral can expand up to 20 times its original volume when heated at high temperatures (around 1600°F or 870°C).
3. Applications:
   • Horticulture: Perlite is widely used in horticulture and gardening. Its lightweight and porous nature provide excellent aeration and drainage in soil, promoting healthy root development for plants.
   • Construction: In construction, expanded perlite is used as insulation material in lightweight concrete and plaster. Its low thermal conductivity makes it an effective insulator.
   • Industrial Uses: Perlite finds applications in various industries, including filtration, where it is used as a filtering agent, and in the manufacturing of fire-resistant doors and panels.
4. Horticultural Benefits:
   • Perlite is a popular soil amendment in gardening and horticulture due to its ability to improve soil structure.
   • It prevents soil compaction, allowing better water retention and drainage.
   • The aeration provided by perlite promotes optimal root growth by preventing the soil from becoming too dense.
5. Expanded vs. Unexpanded Perlite:
   • Unexpanded perlite is the raw material that undergoes expansion when heated.
   • Expanded perlite, with its increased volume and lightweight characteristics, is the more commonly used form in various applications.
6. Mining and Production:
   • Perlite is mined from volcanic deposits around the world, with notable sources in the United States, Greece, Turkey, and other volcanic regions.
   • The mining process involves extraction, crushing, and, in the case of expanded perlite, heating to achieve the desired expansion.