Elemental Composition (by mass)
| Element | Mass % | Visual |
|---|---|---|
| O Oxygen | 45.94% | |
| Si Silicon | 24.20% | |
| Al Aluminum | 15.50% | |
| Na Sodium | 13.20% | |
| H Hydrogen | 1.16% |
Computed from simplified end-member formula. Solid-solution series, water content, and trace substitutions cause real-world variation.
IMA Abbreviation (Whitney-Evans 2010)
Ntr
→ Natrolite
Zeolite — acicular
Standard symbol from American Mineralogist (Whitney & Evans, 2010). Used in thin-section labeling, phase diagrams, and IMA-style species records.
Mohs 5–5.5
Vickers (~) 540 HV
Knoop (~) 620 HK
Geological setting
VolcanicPlutonic igneous
Element composition by mass
Formula: Na₂Al₂Si₃O₁₀·2H₂O · molar mass: 362.2 g/mol
| O | 48.59% | |
| Si | 23.26% | |
| Al | 14.9% | |
| Na | 12.69% | |
| H | 0.56% |
Computed from atomic weights (IUPAC 2021). Site-occupancy groups (Fe,Mn) split equally.
Mohs Hardness
5–5.5
Natrolite sits at 5–5.5 on the Mohs scale — can be scratched by a steel knife.
Colors:
Streak
White
White
Crystal system
Orthorhombic
Orthorhombic
SilicatesSilicates (Tectosilicates — Zeolites)
TL;DR · 1 min read
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 (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.