Natrolite (Na₂Al₂Si₃O₁₀·2H₂O) is the sodium end-member of the natrolite zeolite series and a defining species of the zeolite group. Its name from Latin “natrium” (sodium) reflects its dominant cation. Natrolite forms acicular needles and fibrous radiating sprays in basalt and nepheline-syenite cavities, often with colorless to white crystals reaching exceptional clarity. Mont Saint-Hilaire (Quebec) and the Berufjordur basalts of Iceland are the most prized collector localities.
Key Facts
- Mohs hardness 5–5.5 — slightly harder than other common zeolites.
- Orthorhombic; acicular needles, fibrous sprays, and rare blocky prisms.
- Forms a continuous series with mesolite and scolecite (Ca-bearing variants).
- Strong pyroelectric and piezoelectric properties — exhibits charge under heat or pressure.
- Common companion to apophyllite, stilbite, and heulandite in basalt cavities.
Notable Localities
Mont Saint-Hilaire (Quebec, Canada) produces large gem-clear blocky crystals from nepheline-syenite. Berufjordur (Iceland) yields radiating sprays. Pune basalts (India) supply needle aggregates.
Found at these Localities
- Maharashtra Deccan Traprock Zeolites (马哈拉施特拉德干玄武岩沸石产地)
- Benitoite Gem Mine (蓝锥矿宝石矿)
- Filipinas Mine (Los Chupaderos) (菲利皮纳斯矿(拉利玛产地))
- Magnet Cove (马格尼特湾碱性杂岩)
- Mont Saint-Hilaire (圣希莱尔山(魁北克))
