An experimental study of the Liesegang phenomenon and crystal growth in silica gels

Sharbaugh, A. H.

doi:10.1021/ed066p589

Cited by 22 publications

(27 citation statements)

References 5 publications

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“…The chemical reactions between the salts lead to a slightly soluble product that precipitates discontinuously in bands parallel to the diffusion front's surface. This phenomenon, called Liesegang bands, has been widely studied because it offers a model to explain a great variety of formations in nature, ranging from agate rocks and gold veins to the growth of bacterial rings in agar and gallstones [8][9][10][11][12][13][14][15]. The patterns appear to follow some general laws.…”

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Crossover between Spatially Confined Precipitation and Periodic Pattern Formation in Reaction Diffusion Systems

et al. 1996

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We have observed a crossover between a spatially confined precipitation regime and periodic pattern formation regime. This unusual behavior was observed when electrolyte solutions of Na 2 HPO 4 and CaCl 2 were allowed to diffuse into an agarose gel from opposite ends. The formation of the confined precipitate occurs when the electrolyte flux J is the same at both sides of the gel. The time of formation and the width of the precipitate are a function of J and both follow the scaling relation v ϳ ͑J͞D͒ 2b with b 0.40 6 0.2 and D the diffusion coefficient. The growth of periodic bands of precipitate was observed when J was different at both gel ends. [S0031-9007(96)01256-2]

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Crossover between Spatially Confined Precipitation and Periodic Pattern Formation in Reaction Diffusion Systems

et al. 1996

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“…These authors proposed that 'wood-grained cherts' have palaeoenvironmental significance in that they are found exclusively in high-productivity, foreslope sediments deposited within the oxygen minimum zone and developed a genetic model for these structures invoking inward diffusion of carbonate in a sulphate-reducing, organic-rich, diagenetic environment. Precipitation of an outward sequence of concentric bands of dolomite would occur as opal-CT chert nodules converted to quartz, releasing Mg 2+ in the process; in their view, the resulting bands formed within crossdiffusion gradients of Mg 2+ , Ca 2+ and CO 3 2) , in a manner similar to the origin of Liesegang rings (Prager, 1956;Sharbaugh & Sharbaugh, 1989;Iszák & Lagzi, 2005). Similar alternations of quartz and siliceous dolomite are present in a small number (< 5%) of quartz-phase chert spheroids from several outcrop sections of the Monterey Formation (El-Shishtawy, 1990;Behl, 1992 The measured porosity of surrounding diatomite and the differential compaction of outer chert laminations suggest that the chert spheroid had completely formed within diatomaceous ooze that still retained > 78 to 83% porosity.…”

Section: Previous Work On Chert Spheroids and Similar Structuresmentioning

confidence: 99%

Chert spheroids of the Monterey Formation, California (USA): early‐diagenetic structures of bedded siliceous deposits

Behl¹

2011

Sedimentology

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Chert spheroids are distinctive, early‐diagenetic features that occur in bedded siliceous deposits spanning the Phanerozoic. These features are distinct in structure and genesis from similar, concentrically banded ‘wood‐grain’ or ‘onion‐skin’ chert nodules from carbonate successions. In the Miocene Monterey Formation of California (USA), chert spheroids are irregular, concentrically banded nodules, which formed by a unique version of brittle differential compaction that results from the contrasting physical properties of chert and diatomite. During shortening, there is brittle fracture of diatomite around, and horizontally away from, the convex surface of strain‐resistant chert nodules. Unlike most older siliceous deposits, the Monterey Formation still preserves all stages of silica diagenesis, thus retaining textural, mineralogical and geochemical features key to unravelling the origin of chert spheroids and other enigmatic chert structures. Chert spheroids found in opal‐A diatomite form individual nodules composed of alternating bands of impure opal‐CT chert and pure opal‐CT or chalcedony. With increased burial diagenesis, surrounding diatomite transforms to bedded porcelanite or chert, and spheroids no longer form discrete nodules, yet still display characteristic concentric bands of pure and impure microcrystalline quartz and chalcedony. Petrographic observations show that the purer silica bands are composed of void‐filling cement that precipitated in curved dilational fractures, and do not reflect geochemical growth‐banding in the manner of Liesegang phenomena invoked to explain concentrically banded chert nodules in limestone. Chertification of bedded siliceous sediment can occur more shallowly (< 100 m) and rapidly (< 1 Myr) than the bulk silica phase transitions forming porcelanite or siliceous shale in the Monterey Formation and other hemipelagic/pelagic siliceous deposits. Early diagenesis is indicated by physical properties, deformational style and oxygen‐isotopic composition of chert spheroids. Early‐formed cherts formed by pore‐filling impregnation of the purest primary diatomaceous beds, along permeable fractures and in calcareous–siliceous strata.

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“…In chemical systems, chemical gardens [3][4][5][6] and the regular precipitation bands evolving through simple precipitation reactions called Liesegang structures [7][8][9][10] are known for centuries. One of the most studied reactions yielding intriguing spatiotemporal structures is the Belousov-Zhabothinsky reaction where malonic acid is oxidized by bromate in an acidic medium [11].…”

Section: Introductionmentioning

confidence: 99%

Double-diffusive cellular fingering in the horizontally propagating fronts of the chlorite–tetrathionate reaction

Rica

Pópity-Tóth

Horváth

et al. 2010

Physica D: Nonlinear Phenomena

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a b s t r a c tHorizontally propagating chemical fronts have been studied in the acid-catalyzed chlorite-tetrathionate reaction. Unusual cellular fingers develop in a relatively thin solution layer. Double-diffusive convection is among the driving forces in the pattern formation arising from the addition of a polyelectrolyte which immobilizes and reversibly removes the autocatalyst hydrogen ion in a controlled manner and drastically slows down the front. Convection therefore becomes significant in the thin horizontal solution layer. To corroborate our results we have measured the solution densities and viscosities, and determined the diffusion coefficients by PFGSE 1 H-NMR.

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An experimental study of the Liesegang phenomenon and crystal growth in silica gels

Abstract: About 100 diffusion experiments were carried out in separate test tubes; the growth of the resulting crystals and precipitates was extremely interesting to watch and often very colorful and spectacular.

Cited by 22 publications

References 5 publications

Crossover between Spatially Confined Precipitation and Periodic Pattern Formation in Reaction Diffusion Systems

Crossover between Spatially Confined Precipitation and Periodic Pattern Formation in Reaction Diffusion Systems

Chert spheroids of the Monterey Formation, California (USA): early‐diagenetic structures of bedded siliceous deposits

Double-diffusive cellular fingering in the horizontally propagating fronts of the chlorite–tetrathionate reaction

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