heulandite


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Related to heulandite: natrolite, Thomsonite, stilbite

heulandite

[′hyü·lən‚dīt]
(mineralogy)
CaAl2Si6O16·5H2O A zeolite mineral that crystallizes in the monoclinic system; often occurs as foliated masses or in crystal form in cavities of decomposed basic igneous rocks.
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Structural classification Identified zeolitic phases Heulandite group (C4-C4-T1) stellerite, stilbite, stellerite-Na, Stilbite-Ca Chabazite group (C6) chabazite, levyne, chabazite-Ca, chabazite-Na Analcime group (C4-C4) analcime, wairakite, analcime-Mg Natrolite group (C4-T1) natrolite, thomsonite, thomsonite-Ca Phillipsite group (C4) phillipsite, phillipsite-Na Laumontite group (C8) laumontite
Heulandite was not found in this part of the mineralized zone.
The magnitude of N[H.sub.4.sup.+] adsorption would be exacerbated by the presence of soil materials with a strong preference for N[H.sub.4.sup.+] such as heulandite in Zeolite (Ming and Mumpton 1989) and 2:1 layer aluminosilicates (Barbayiannis et al.
Because of the difficulty of discriminating accurately heulandite from clinoptilolite, we use the term "heulandite" to include both minerals.
Datolite and prehnite are still present; however, albite and calcite become more common, as do the zeolites heulandite and stilbite.
Prehnite, apophyllite, calcite, hematite, heulandite and sulfides are known to form on the crystal faces.
If you have a hundred specimens of heulandite in your collection, unless you run a test on every single specimen you cannot reliably assign to them their correct modern names.
Calcite crystals typically cover first-generation crystals of heulandite, and are themselves covered by later mordenite.
The delicate "feathers" densely populate the matrix plates, on which pinkish crusts of heulandite also host pale green, blocky fluorapophyllite crystals to 2 cm.
Early in 2005, a dealer in Changsha offered a specimen, presumably of heulandite, from a new discovery at Fengjiashan.
Bright orange to red-orange, smooth-surfaced, radial-aggregate spheres of ferrierite crystals with a medium to dull luster reach 2.5 cm in diameter; the spheres line seams in basalt, associated with microcrystals of heulandite and mordenite.
Spence (1920) noted the presence of stilbite and heulandite in fluorapatite-phlogopite skarn deposits, and Hoffman (1901) reported faujasite from the Daisy mine, Papineau Co., Quebec.