Natrolite

Natrolite was named by Martin Heinrich Klaproth in 1803. The name is derived from Greek "natron" - soda, in reference to the sodium content and "lithos" - stone.

Natrolite produce some fine crystal specimens. The mineral is also often found as compact fibrous aggregates. It is usually white or colorless, sometimes reddish, greenish or yellowish. The luster is vitreous, finely fibrous specimens have silky luster.

Colourless facet rough natrolite is seldom.

Natrolite Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 

Natrolite Gemstones by Size

This table shows distribution of Natrolite gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:0.61 cts
Heaviest:4.98 cts
Average:1.97 cts
Total photos:12
Do you have a larger Natrolite? Why not upload a photo?
0.61ct to 1.05ct1.05ct to 1.48ct1.48ct to 1.92ct1.92ct to 2.36ct2.36ct to 2.80ct2.80ct to 3.23ct3.23ct to 3.67ct3.67ct to 4.11ct4.11ct to 4.54ct4.54ct to 4.98ct
General Information
Chemical Formula
Na
 
2
[Al
 
2
Si
 
3
O
 
10
] · 2H
 
2
O
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Photos of natural/un-cut material from mindat.org
Physical Properties of Natrolite
Mohs Hardness5 to 5.5
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Specific Gravity2.20 to 2.26
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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TenacityBrittle
Arthur Thomas, Gemstones (2009)
Cleavage QualityPerfect
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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FractureIrregular
Arthur Thomas, Gemstones (2009)
Optical Properties of Natrolite
Refractive Index1.478 to 1.493
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Optical CharacterBiaxial/+
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Birefringence0.012 to 0.013
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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PleochroismNil
Arthur Thomas, Gemstones (2009)
DispersionWeak
Arthur Thomas, Gemstones (2009)
Colour
Colour (General)Colourless, yellowish, white, gray, brownish
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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TransparencyTransparent,Translucent,Opaque
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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LustreVitreous
Arthur Thomas, Gemstones (2009)
Crystallography of Natrolite
Crystal SystemOrthorhombic
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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HabitFibrous aggregate
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Geological Environment
Where found:Occurs in cavities in amygdaloidal basalts and related igneous rocks in association with other zeolites
Michael O’Donoghue, Gems, Sixth Edition (2006)
Inclusions in Natrolite
Common rod-like yellowish-brown inclusions (acmite) - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 9
Further Information
Mineral information:Natrolite information at mindat.org
Significant Gem Localities
Canada
 
  • Québec
    • Montérégie
      • La Vallée-du-Richelieu RCM
        • Mont Saint-Hilaire
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 432
Russia
 
  • Murmansk Oblast
USA
 
  • New Jersey
    • Somerset Co.
      • Bridgewater Township
Copyright © Jolyon & Katya Ralph 1993-2019. Site Map. Locality, gem & photograph data are the copyright of the individuals who submitted them. For more information please contact the . Gemdat.org is an online information resource dedicated to providing free gemmological information to all.