Nucleation of aragonite upon carbonation of calcium oxide and calcium hydroxide at ambient temperatures and pressures: a new indicator of fire-related human activities

Toffolo, Michael B.; Boaretto, Elisabetta

doi:10.1016/j.jas.2014.05.020

Cited by 61 publications

(69 citation statements)

References 100 publications

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“…These peaks were well matched with ICSD 032100 of aragonite. Since aragonite is thermodynamically unstable compared to calcite, transformation of calcite to aragonite at high temperature under ambient condition is impossible [31,32]. Several paths were taken by ACS to form atmospheric aragonite.…”

Section: Resultsmentioning

confidence: 99%

Effects of Calcination on the Crystallography and Nonbiogenic Aragonite Formation of Ark Clam Shell under Ambient Condition

Loy¹,

Матори

Lim³

et al. 2016

Advances in Materials Science and Engineering

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This paper presents a study of crystallographic evolution of disposed ark clam shell (ACS) after calcination at 400–1400°C which was kept at room temperature under ambient condition in Malaysia during nine months. A better understanding of hydration and recarbonation of ACS powder (≤63 μm) after calcination was discovered by PXRD and FTIR. The research focuses on the crystallographic transformation, biogenic calcite decomposition, and unusual atmospheric aragonite formation in ACS after calcination and atmospheric air exposure. Ex situ PXRD showed calcite present in ACS at ≤900°C. ACS transformed to pyrogenic fcc CaO at ≥800°C after three months. Long term atmospheric air exposure of decarbonized ACS caused nucleation of nonbiogenic aragonite, vaterite, calcite, and portlandite. However, in situ PXRD analysis of ACS at instantaneous temperature without cooling process does not indicate the presence of aragonite, vaterite, and portlandite crystals. FTIR spectra revealed CaO–CO2bond in ACS dissociated with temperature (600–900°C) to form CaO and CO2. Ca–OH bond was also traced in FTIR spectra of ≥700°C. It resulted by hydroadsorption of CaO with H2O in atmospheric air.

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Section: Resultsmentioning

confidence: 99%

Effects of Calcination on the Crystallography and Nonbiogenic Aragonite Formation of Ark Clam Shell under Ambient Condition

Loy¹,

Матори

Lim³

et al. 2016

Advances in Materials Science and Engineering

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“…These are artifacts or sediments altered because of fire temperatures. Depending on the temperature threshold, such heating can result in important structural and mineralogical transformations (Aldeias et al 2016a(Aldeias et al , 2016bChu et al 2008;Elbaum et al 2003;Maki, Homburg, and Brosowske 2006;Schmidt 2013;Schmidt et al 2013;Stiner et al 1995;Toffolo and Boaretto 2014;Weiner et al 2015). Therefore, thermally altered artifacts (bones, lithics, shells, seeds, etc.…”

Section: Fire Proxies and Their Contextual Arrangementmentioning

confidence: 99%

Experimental Approaches to Archaeological Fire Features and Their Behavioral Relevance

Aldeias¹

2017

Current Anthropology

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The uses and functions of fire in early human adaptations are commonly debated and at times very controversial topics. It is important to recognize under what circumstances and conditions specific fire-related traces can be produced and preserved in the archaeological record. Currently, a growing body of data is emerging on the application of experimental research to the study of archaeological hearths and their residues. In this review, I draw together aspects of such available experimental data, particularly those pertaining to the sedimentary expression and components produced during simple campfires. I highlight not only what one can find in ideal preservation conditions but also what type of indirect alteration proxies can be expected to survive in the archaeological record. I then discuss the implications of such data for analyzing anthropic fire features, their timing, and their meaning in terms of behavioral complexity in the use and manufacture of fire during the Paleolithic.

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“…The theoretical study by Poduska et al [21] showed that the displacement between different curves is a product of different degrees of short-range atomic order in crystals formed by different mechanisms. recently shown that the same mechanism of formation can lead to the nucleation of aragonite, one of the metastable polymorphs of CaCO3, in different amounts based on the starting CaCO3 substrate and environmental settings in magnesium-free lime plasters [12]. In nature, aragonite and calcite may form through different processes, such as precipitation in supersaturated solutions, precipitation in boiling water at hot springs, slow crystal growth in speleothems and spar, and biomineralization [11,13].…”

Section: Introductionmentioning

confidence: 99%

“…Since anthropogenic carbonates usually nucleate as calcite, their degree of atomic order is determined using calcite grinding curves. However, pyrogenic aragonite recently produced in experimental magnesium-free lime plasters together with calcite, and observed in archaeological carbonate-based materials [12,31,32,[34][35][36], has not been considered in previous infrared grinding curves. This lack of structural characterization hinders a proper assessment of the degree of preservation of lime binders comprised of aragonite-calcite mixtures, as to date there is no method for separating the contributions of the two polymorphs when they occur together in the same infrared spectrum.…”

Section: Introductionmentioning

confidence: 99%

FTIR-Based Crystallinity Assessment of Aragonite–Calcite Mixtures in Archaeological Lime Binders Altered by Diagenesis

et al. 2019

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Lime plaster and mortar are pyrotechnological materials that have been employed in constructions since prehistoric times. They may nucleate as calcite and/or aragonite under different environmental settings. In nature, aragonite and calcite form through biogenic and geogenic processes that lead to different degrees of atomic order. The latter is a result of defects in the crystal lattice, which affect the properties of crystals, including their interaction with infrared light. Using Fourier transform infrared spectrometry (FTIR) with the KBr pellet method, it is possible to exploit these differences and assess the degree of atomic order of aragonite and calcite crystals and thus their mechanisms of formation. Here we use FTIR to characterize the degree of short-range atomic order of a pyrogenic form of aragonite recently observed in experimental and archaeological lime binders. We show that pyrogenic aragonite has a unique signature that allows its identification in archaeological sediments and lime binders of unknown origin. Based on these results, we developed a new FTIR-based method to assess the integrity and degree of preservation of aragonite and calcite when they occur together in the same material. This method allowed a better assessment of the diagenetic history of an archaeological plaster and finds application in the characterization of present-day conservation materials, such as lime plaster and mortar, where different polymorphs may nucleate and undergo recrystallization processes that can alter the mechanical properties of binders.

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Nucleation of aragonite upon carbonation of calcium oxide and calcium hydroxide at ambient temperatures and pressures: a new indicator of fire-related human activities

Cited by 61 publications

References 100 publications

Effects of Calcination on the Crystallography and Nonbiogenic Aragonite Formation of Ark Clam Shell under Ambient Condition

Effects of Calcination on the Crystallography and Nonbiogenic Aragonite Formation of Ark Clam Shell under Ambient Condition

Experimental Approaches to Archaeological Fire Features and Their Behavioral Relevance

FTIR-Based Crystallinity Assessment of Aragonite–Calcite Mixtures in Archaeological Lime Binders Altered by Diagenesis

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