Terminology

• Expanded perlite: perlite popped by heating
• Obsidian: volcanic glass from which perlite forms by hydration

History and demand

Sourcing

• 2018: about 4.6 million tonnes produced worldwide; China, Turkey, Greece, USA, Armenia, and Hungary lead; world reserves about 700 million tonnes

Composition and production

Raw materials

• Amorphous volcanic glass, typically formed by hydration of obsidian

Manufacturing process

• Softens at 850 to 900°C (1,560 to 1,650°F) and expands to 7 to 16 times its original volume

Properties

Physical

• Density, raw: about 1,100 kg/m3 (about 69 lb/ft3)
• Density, expanded: about 30 to 150 kg/m3 (about 1.9 to 9.4 lb/ft3)

Uses in buildings

Building elements

• Interior Plaster: lightweight plaster aggregate
• Wall and Roof Insulation: loose-fill insulation
• Acoustic Wall and Ceiling Panels: ceiling tile component

Pros and cons

Pros

• Very low expanded density
• Used in plaster, concrete, mortar, and insulation

Cons

• Silica dust requires goggles and filtering masks when handling large quantities

Sustainability

Health

• Contains silicon dioxide; OSHA limit 15 mg/m3 total and 5 mg/m3 respirable (8 hours); NIOSH 10 mg/m3 total and 5 mg/m3 respirable

Manufacturing and cost

Main manufacturers and suppliers

Trade association: Perlite Institute.

Sources

• Wikipedia: Perlite, https://en.wikipedia.org/wiki/Perlite
• Wikimedia Commons: Perlite1.jpg, photo by KENPEI (CC BY-SA 3.0), https://commons.wikimedia.org/wiki/File:Perlite1.jpg