Natrolite

 

Natrolite

 

Discovered in 1803; IMA status: Valid (pre-IMA; Grandfathered)

 

Chemistry

 

 

Chemical Formula:

Na2Al2Si3O10 • 2H2O

 

Hydrated Sodium Aluminum Silicate

Molecular Weight:

380.22 gm

Composition:

Sodium

12.09 %

Na

16.30 %

Na2O

 

Aluminum

14.19 %

Al

26.82 %

Al2O3

 

Silicon

22.16 %

Si

47.41 %

SiO2

 

Hydrogen

1.06 %

H

9.48 %

H2O

 

Oxygen

50.49 %

O

 

 

 

 

100.00 %

 

100.00 %

= TOTAL OXIDE

 

 

Classification

   

   

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/J.21-10

Nickel-Strunz 10th Ed. ID:

9.GA.05

 

9 : SILICATES (Germanates)
G : Tektosilicates with zeolitic H
2O; zeolite family
A : Zeolites with T
5O10 Units – The Fibrous Zeolites

Related to:

Zeolite Group. Natrolite Subgroup. Dimoroh of Gonnardite.

Members of Group:

Zeolite Group: Amicite, Barrerite, Bellbergite, Bikitaite, Boggsite, Brewsterite, Chabazite, Chabazite-Lévyne Subgroup, Clinoptilolite, Cowlesite, Dachiardite-Na, Epistilbite, Erionite, Faujasite Subgroup, Ferrierite, Garronite, Gismondine, Gmelinite, Gobbinsite, Goosecreekite, Harmotome, Heulandite, Laumontite, Lévyne, Mazzite, Merlinoite, Montesommaite, Mordenite, Offretite, Paulingite, Pollucite, Stellerite, Stilbite, Thomsonite, Tschernichite, Wairakite, Willhendersonite, Yugawaralite

Members of Subgroup:

Natrolite Subgroup: Gonnardite, Mesolite, Natrolite, Paranatrolite, Scolecite

Varieties:

Bergmannite, Galactite, Germanate-natrolite, Kondrikovite, Mooraboolite, Spreustein

Synonyms:

Ædelite (of Kirwan), Aedelite, Apoanalcite, Bergmannite, Crocalite, Crockalite, Epinatrolite, Fargite, Feather Zeolite, Galactite, Lehuntite, Mealy Zeolite, Mesotype, Natronite (of ?), Needlestone, Portite

Crystal Data

   

   

Crystallography:

Orthorhombic - Pyramidal

Crystal Habit:

Crystals short to long prismatic, to 1 m, striated. In stellate or interlacing groups; also radiating fibrous, granular, or compact, massive.

Twinning:

On {110}, {011}, {031}

 

 

Physical Properties

   

 

Cleavage:

Perfect on {110}, parting on {010}

Fracture:

Irregular/uneven

Tenacity:

Brittle

Moh's Hardness:

5.5 - 6.0; Vickers: VHN200=1239 - 1467 kg/mm2

Density:

2.20 - 2.26 (g/cm3)

Luminescence:

Fluorescent; SW UV = yellow-orange, pale green, LW UV = yellow-orange, greenish white

Radioactivity:

Not Radioactive

Other:

Piezoelectric and Pyroelectric

 

 

Optical Properties

   

   

Color:

Colorless, white, gray, bluish, pink, yellowish white

Transparency:

Transparent to translucent

Luster:

Vitreous to pearly, silky

Refractive Index:

1.473 - 1.496  Biaxial ( + )

Birefringence:

0.0120 - 0.0130

Dispersion:

Weak, r < v (0.005)

Pleochroism:

Weak; X = colorless, Y = colorless, Z = colorless

 

 

Occurances

   

   

Geological Setting:

In cavities in amygdaloidal basalts and related igneous rocks, one of the last minerals to form; fills seams in granite, gneiss, and syenite.

Common Associations:

Zeolites, Calcite, Nepheline, Sodalite, Quartz

Common Impurities:

Ca, K

Type Locality:

Hohentwiel, Singen, Hegau, Baden-Württemberg, Germany 

Year Discovered:

1803

View mineral photos:

Natrolite Mineral Photos and Locations

 

 

Unusual Gem Categories

   

   

 

Fluorescent Gems, Piezoelectric Gems, Pyroelectric Gems

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 

Natrolite is one of the more popular and well known members of the Zeolite Group of minerals that includes over 40 minerals and these gem-type minerals: Analcime, Barrerite, Chabazite, Epistilbite, Gmelinite-Na, Goosecreekite, Mordenite, Natrolite, Pollucite, Scolecite, Stellerite, Stilbite, Thomsonite and Yugawaralite. Natrolite usually forms as elongated crystals so faceted gems are often cut as elongated emerald cut gems. Natrolite gems are colorless and have weak dispersion and might be considered somewhat uninteresting except for the fact that Natrolite is both piezoelectric and pyroelectric and commonly exhibits yellow to orange or pale green fluorescence under both shortwave and longwave UV light.

Natrolite was discovered in 1803 at Hohentwiel, Singen, Hegau, Baden-Württemberg, Germany. Hohentwiel is an extinct volcano. Natrolite was named by German chemist Martin Heinrich Klaproth (1743-1817) from the Latin word natron meaning soda, for its sodium content, and the Greek word λίθος, (lithos) meaning stone.

Crystals can be found in many locations worldwide but gem quality crystals are relatively rare. Notable occurances are the Höwenegg quarry, Hegau, Baden-Württemberg, Germany (the Type Locality); Puy de Marman, near Veyre, Puy-de-Dôme, France. In the Dean quarry, St. Keverne, Lizard Peninsula, Cornwall, England; White Head, County Antrim, Ireland; Langesundsfjord and Tvedalen areas, Norway; Khibiny and Lovozero massifs, Kola Peninsula, Russia (large crystals); in the USA, at Bound Brook, Somerset County, New Jersey; from north of Livingstone, Park County, Montana; around Springfield, Lane County, Oregon; and at the Gem mine, San Benito County, California, USA. In Canada, huge crystals from the Johnston asbestos mine, near Thetford, and from Mont Saint-Hilaire, Quebec; in the Bay of Fundy district, Nova Scotia; and along the Ice River, British Columbia.

  
Natrolite gems for sale:

Natrolite-001
please click on picture

Gem:

Natrolite

Stock #:

NATRO-001

Weight:

5.7730 ct

Size:

17.22 x 10.60 x 6.71 mm

Shape:

Cushion w/ Checkerboard table

Color:

Colorless

Clarity:

Eye Clean

Origin:

Bound Brook, New Jersey, USA

Treatment:

None (natural)

Price:

$430.00  RESERVED   [ Make an offer ]

Pictures are of the actual gem offered for sale.
Gem images are magnified to show detail.

Natrolite-001
please click on picture

Please click on the pictures above for a larger view.

A very, very large, bright and beautiful Natrolite from Bound Brook, New Jersey that is eye clean! A true rarity at this size and clarity!


Natrolite-002

Gem:

Natrolite

Stock #:

NATRO-002

Weight:

0.7955 ct

Size:

5.56 x 5.47 x 4.22 mm

Shape:

Princess

Color:

Colorless

Clarity:

Eye Clean - SI2

Origin:

Bound Brook, New Jersey, USA

Treatment:

None (natural)

Price:

SOLD (but we have others)

Pictures are of the actual gem offered for sale.
Gem images are magnified to show detail.

Natrolite-002

A very rare gem from an unusual US location that is beautifully faceted.


 


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