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Related to Nontronite: saponite, Palygorskite


Na(Al,Fe,Si)O10(OH)2 An iron-rich clay mineral of the montmorillonite group that represents the end member in which the replacement of aluminum by ferric ion is essentially complete. Also known as chloropal; gramenite; morencite; pinguite.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a mineral of the montmorillonite-vermiculite group. In terms of its crystallochemical structure, nontronite is a phyllosilicate. Its chemical composition is

Fe23+ [AlxSi4-xO10](OH)2 · Na0.33(H2O)4

It contains significant quantities of Al2 OO3 (up to 14 percent) and MgO (up to 8 percent), as well as small quantities of CaO (up to 2 percent), K2O, Na2O, and sometimes NiO and Cr2O3. The basis of the structure of nontronite is a three-layer unit of the talc or pyrophyllite type—two layers of SiO tetrahedrons separated by an octahedral layer of FeO6; between the unit layers are molecules of water with exchange bases of Na. Al replaces the Si in the tetrahedrons.

Nontronite is an isomorphic mixture of nontronite proper and montmorillonite. It crystallizes in the monoclinic system. Aggregates of nontronite are usually compact, claylike, and crypto-crystalline, less frequently in the form of pseudomorphs after dark-colored minerals. Their color ranges from greenish yellow to dark green. Their hardness on Mohs’ scale is about 2, and their density is up to 2,100 kg/m3. Nontronite is a typical super-gene mineral, which forms primarily upon the weathering of iron-bearing silicates of various ultrabasic igneous and meta-morphic rocks. Nontronite masses rich in nickel are economically important.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Ding, "Near-infrared spectroscopic study of nontronites and ferruginous smectite," Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, vol.
Another clay mineral commonly recorded in the low temperature hydrothermal alteration of basalts is nontronite, which has been described in the literature as genetically related to bacteria in marine white smoker chimneys from the Galapagos Spreading Center and Mariana Trough by Kohler et al.
Control of Fe(III) Site Occupancy on the Rate and Extent of Microbial Reduction of Fe(III) in Nontronite. Geochimica et Cosmochimica Acta, 69(23): 5429-5440.
The vesicles and fractures in basalts were gradually filled up with secondary minerals, developing amygdales and veins usually showing mineral zoning distribution though, in some cases, they were not completely filled Figure 5a gives an example of the occurrence of a mixed layer of celadonite (Fe-rich mica) and non-tronite (Fe-rich smectite) and vesicles commonly lined by these mineral phases Celadonite is usually green and botroidal and has fibrous spheroidal morphology, having detectable striated birefringence under crossed nicols Nontronite is typically brown in transmitted light and does not have a discernable structure except for banding parallel to the cavity wall It occasionally exhibits geopetal features.
Analysis revealed that it consisted of kaolinite, dickite (a closely related clay mineral to kaolinite), nontronite, (a smectite, similar to bentonite, where iron replaces alumina in the crystal lattice), the remainder being quartz.
Higher grade limonite acid pressure leaching with particular reference to the Calliope project in New Caledonia has been discussed by Russel(17) and contrasted to the lower grade nontronite clays at Murrin Murrin.
O'Reilly, "Rapid precipitation of amorphous silica in experimental systems with nontronite (NAu-1) and Shewanella oneidensis MR-1," Geochimica et Cosmochimica Acta, vol.
The research has been focused on the basic clay mineral specimens (kaolinite, montmorillonite, nontronite, illite, chlorite and vermiculite) including micas (muscovite, biotite) and the associated minerals (quartz, feldspar, carbonates and sulphates).
(1942) books"; schorl of "tremendous size"; nontronite Davib mine Schorl; green elbaite Frommurze et al.
However, under a stronger or longer interaction, the neoformation of trioctahedral smectites such as saponite-stevensite, Fe(II)-rich saponite or dioctahedral nontronite (as a function of the Mg and Fe(II)/Fe(III) activities in the environment, respectively), corrensite and Fe-Mg-rich chlorite may occur as recorded in some active geothermal and diagenetic systems (Yamada and Nakasawa, 1993; Beaufort et al., 1995, 2001; Bril et al., 1996; Robinson and Santana de Zamora, 1999; Mayayo et al., 2000; Hover and Ashley, 2003).
Idealized crystallochemical formulae of most common dioctahedral smectites: montmorillonite, [([Al.sub.1.67][Mg.sub.0.33]).sup.VI][([Si.sub.4]).sup.IV][O.sub.10] [(OH).sub.2][[M.sup.+].sub.0.33].n[H.sub.2]O, beidellite, [([Al.sub.2]).sup.VI][([Si.sub.3.67][Al.sub.0.33]).sup.IV] [O.sub.10][(OH).sub.2]][[M.sup.+].sub.0.33].n[H.sub.2]O, nontronite, [[([Fe.sup.3+]).sub.2].sup.VI][([Si.sub.3.67][Al.sub.0.33]).sup.IV] [O.sub.10][(OH).sub.2][[M.sup.+].sub.0.33].n[H.sub.2]O Example of a trioctahedral smectite: saponite, [([Mg.sub.3]).sup.VI][([Si.sub.3.67][Al.sub.0.33]).sup.IV] [O.sub.10][(OH).sub.2][[M.sup.+].sub.0.33] .n[H.sub.2]O.
In other places, the iron formed green, iron-rich clay (nontronite).