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 ?
Natrolite, analcime, and thomsonite are typically found as alteration products of mafic rocks, where they develop within late stage alteration assemblages [47, 90].
Qualitative XRD analysis led to identifying a variety of zeolite species, including analcime, as the dominant zeolytic phase, followed by chabazite, natrolite, thomsonite, wairakite, stilbite, stilbite-Ca, phillip-site and stellerite-Na, thomsonite-Ca, chabazite-Ca and chabazite-Na, with minor stellerite, laumontite, levyne, phillipsite-Na, and gyrolite Other secondary minerals associated with zeolites were celadonite (Fe-rich mica), nontronite (Fe-rich smectite), greigeite (iron sulide mineral), koninckite or bobierrite (phosphates), alunite (sulphate), truscottite (silicate), calcite or dolomite, and quartz Nontronite occurred in most samples.
"With natrolite, people have always said you can't get Eu3+ in there," study co-author Thomas Vogt said.
This mineral association frequently shows simple accretionary features, such as crustifications (e.g., analcime I, Ba-bearing phillipsite-Ca, gismondine, rarely gmeliniteCa) and development of well-defined crystals or fibrous aggregates of natrolite and phillip-site-Ca growing from the walls into open space.
The natrolite syenite sample was collected from Fengcheng City of Liaoning Province (China) and natrolite syenite powder (particle size < 74 [micro]m) for this research was prepared by crushing and grinding.
Natrolite is an extremely rare zeolite at the Fanwood quarry; specimens were discovered on one occasion as jumbles of acicular crystals, no longer than 1 cm, on prehnite in a diapiric amygdule.
Mesolite is generally milky white and fibrous with fibres larger than those of natrolite. It can also be massive, white, and dull.
Albite has also been seen as pseudomorphs after natrolite crystals.
An article in the September-October 2000 Mineralogical Record and an update in May-June 2007 made clear that the Millington is, as regards specimens, the newest of the many "traprock" quarries of northern New Jersey, and that its beautiful natrolite, pectolite, datolite and apophyllite specimens rank among this famous area's best.
4) composed primarily of natrolite. It is located in urtite rock enriched by pyroxene (aegirine-diopside), titanite and fluorapatite.
To his amazement, he found the ground there littered with thousands of blue gems that had weathered out of the natrolite veins and accumulated in the surface.
Although it was soon learned that hydrochloric acid could remove the natrolite that almost always covered the crystals and matrix, the acid treatment was found to take too long, so the miners continued to employ the crude but fast techniques, ruining countless thousands of specimens and gemstones while spreading small crystal fragments all over the area.