Natrolite


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Related to Natrolite: olivine, Scolecite, heulandite, analcime, stilbite

natrolite

[′nā·trə‚līt]
(mineralogy)
Na2 Al2Si3O10·2H2O A zeolite mineral composed of hydrous silicate of sodium and aluminum; usually occurs in slender acicular or prismatic crystals.

Natrolite

 

a mineral of the zeolite family with chemical composition Na2[Al2Si3O10].2H2O; an aluminosilicate, it is classed according to crystallochemical structure as a tectosilicate. Natrolite crystallizes in the orthorhombic and tetragonal systems to form elongated prismatic or acicular crystals; more rarely, it occurs as compact cryptocrystalline masses. It is usually colorless; sometimes it is grayish or yellowish. Natrolite’s hardness on Mohs’ scale measures 5–5.5, and its density is 2,200–2,500 kg/m3.

Natrolite absorbs H2O, NH3, CO2, H2S, and other substances. It is also known for its ability to exchange base ions in solution for base ions in the structure, a property that has found wide application in industry, primarily in the manufacture of artificial zeolites. Natrolite forms in association with other zeolites and with calcite, quartz, and chlorites in the cavities and fissures of igneous rocks by precipitation from hot aqueous solutions. It is also formed as a result of the hydrothermal changes of nepheline and may be found in the weathering zone of nepheline syenites, as well as in contemporary marine deposits.

M. D. DORFMAN

References in periodicals archive ?
Walker and Parsons (1922) reported analcime, natrolite, thomsonite, and gmelinite, but we have not identified those minerals in our samples.
The most abundant zeolite on the larger island is analcime, whereas gmelinite and chabazite are common and stilbite and natrolite are rare (I.
Chabazite and stilbite are abundant among our studied samples; "heulandite", barrerite, epistilbite, and natrolite are rare.
Gmelinite was reported by Gilpin (1881) and natrolite by Walker and Parsons (1922), but we did not identify those zeolite minerals.
Analcime and natrolite are abundant, mesolite and stilbite are common, and thomsonite, chabazite, laumontite, and "heulandite" are rare.
Na-rich zeolites are represented by natrolite, tetranatrolite, and gmelinite.
Heulandite", mesolite, stilbite, thomsonite, natrolite, tetranatrolite, and epistilbite have been analysed from both the North Shore and Arlington Quarry and can therefore be compared.
The natrolite and tetranatrolite from Arlington Quarry in hand specimen do not differ from those from North Shore and their chemical characteristics are also similar (Fig.