Natrolite

Natrolite is a tectosilicate mineral species belonging to the zeolite group. It is a hydrated sodium and aluminium silicate with the formula NaO.It was named natrolite by Martin Heinrich Klaproth in 1803. Needle stone or needle-zeolite are other names, alluding to the common acicular habit of the crystals, which are often very slender and are aggregated in divergent tufts. Larger crystals have the form of a square prism terminated by a low pyramid, the prism angle being nearly a right angle. The crystals are tetragonal in appearance, though actually orthorhombic. There are perfect cleavages parallel to the faces of the prism. The mineral also often occurs in compact fibrous aggregates, the fibers having a divergent or radial arrangement. Natrolite is readily distinguished From other fibrous zeolites by its optical characteristics.
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Noun
1. a group of minerals of the zeolite family consisting of a hydrous silicate of sodium and aluminum
(hypernym) zeolite

n. natrolite

(n.)
A zeolite occuring in groups of glassy acicular crystals, and in masses which often have a radiated structure. It is a hydrous silicate of alumina and soda.
  

General Information:
 Chemical Formula:
Na2[Al2Si3O10]·2(H2O)
 Composition:
(Molecular Weight = 380.22 gm)
Sodium 12.09 % Na
Aluminum 14.19 % Al
Silicon 22.16 % Si
Hydrogen 1.06 % H 
Oxygen 50.49 % O 
 Empirical Formula:
Na2Al2Si3O10·2(H2O)
 Environment:
Occurs in the cavities of amygdaloidal basalts and other related rocks.
 IMA Status:
Approved IMA
 Locality:
Bohemia of Czechoslovakia.
 Name Origin:
From the Greek natron, "soda," in allusion to sodium content and lithos - "stone."
Physical Properties:
 Cleavage:
[110] Perfect, [010] Imperfect
 Color:
white, colorless, red, yellowish white, or reddish white.
 Density:
2.25
 Diaphaniety:
Transparent to translucent
 Habits:
Acicular - Occurs as needle-like crystals., Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline)., Nodular - Tuberose forms having irregular protuberances over the surfac e.
 Hardness:
5.5-6 - Knife Blade-Orthoclase
 Luminescence:
None.
 Luster:
Vitreous - Silky
 Streak:
white
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