Microstructure of selected aggregate quartz by XRD, and a critical review of the crystallinity index

Marinoni, Nicoletta; Broekmans, Maarten A. T. M.

doi:10.1016/j.cemconres.2013.08.007

Cited by 52 publications

(14 citation statements)

References 18 publications

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“…As shown by the results of X-rd (Figure 7), crystal plane spacing d = 3.34 Å (diffraction angle 2θ = 26.68) was the diffraction characteristic peak of SiO 2 , which is consistent with the reported characteristic peaks of quartz (SiO 2 ) structures (Leite et al, 2000;Marinoni and Broekmans, 2013). In this Figure, two peaks of CaCO 3 (2θ = 26.1 and 2θ = 27.1) were very high, hinting that the content of CaCO 3 was very high.…”

Section: Low Content Of Sio 2 In Shells With Spotssupporting

confidence: 86%

Silicon Dioxide (SiO2) Is the Most Important Component of Spots on the Inner Surface of Mactra veneriformis Shells

Zhang

Wei

et al. 2019

Front. Mar. Sci.

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Yellow-brown spots are often observed on the inner shell surface of the clam Mactra veneriformis sampled in Binhai New Area, Lijin County, Shandong Province, China, negatively impacting its commercial value. In this study, Scanning electron microscopyenergy dispersive spectroscopy (SEM-EDS), X-ray diffraction (X-rd), laser Raman spectrum (LRS), and Fourier infrared spectrum scanning (FT-IR) were used to detect and analyze the composition of spots on the inner shell surface of these clams. Compared with shells without spots, the shells with spots showed significant differences in their silicon contents but no differences in the content of other basic elements; LRS and X-rd examination revealed that, in addition to calcium carbonate particles, there were traces of silica bonds; after the removal of calcium carbonate by using hydrochloric acid, the spectral trend of particles was similar to that of sea sand, which was consistent with the spectral characteristics of SiO 2. Therefore, the spots on the inner shell surface of M. veneriformis are sea sand. These are likely to result from the increased sand content in seawater in the Yellow River Delta, whereby the grains of sand have fallen into the gap between the mantle and shell; thus, the sand becomes encased in the shells as they grow.

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Section: Low Content Of Sio 2 In Shells With Spotssupporting

confidence: 86%

Silicon Dioxide (SiO2) Is the Most Important Component of Spots on the Inner Surface of Mactra veneriformis Shells

Zhang

Wei

et al. 2019

Front. Mar. Sci.

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“…X‐ray powder diffraction (XRPD) analysis of powders extracted from the gigantoproductids confirmed the presence of quartz with a variable crystallinity index (from 5.43 to 7.26 out of a maximum of 10) as calculated following Marinoni & Broekmans (), which revised that of Murata & Norman () (Angiolini et al . , fig.…”

Section: Resultsmentioning

confidence: 78%

The giants of the phylum Brachiopoda: a matter of diet?

et al. 2019

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The species of the brachiopod Gigantoproductus are giants within the Palaeozoic sedentary benthos. This presents a dilemma as living brachiopods have low‐energy lifestyles. Although brachiopod metabolic rates were probably higher during the Palaeozoic than today, the massive size reached by species of Gigantoproductus is nevertheless unusual. By examining the diet of Gigantoproductus species from the Visean (Mississippian, Carboniferous) of Derbyshire (UK), we seek to understand the mechanisms that enabled those low‐metabolism brachiopod species to become giants. Were they suspension feeders, similar to all other brachiopods, or did endosymbiosis provide a lifestyle that allowed them to have higher metabolic rates and become giants? We suggest that the answer to this conundrum may be solved by the identification of the biogeochemical signatures of symbionts, through combined analyses of the carbon and nitrogen‐isotopic compositions of the occluded organic matrix within their calcite shells. The shells are formed of substructured columnar units that are remarkably long and a few hundreds of microns wide, deemed to be mostly pristine based on multiple analyses (petrography, cathodoluminescence (CL), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM)); they contain occluded organic fractions detected by TEM, nuclear magnetic resonance (NMR) and gas chromatography mass spectrometry (GC‐MS) analyses. We conclude that the gigantic size reached by the species of Gigantoproductus is probably the result of a mixotroph lifestyle, by which they could rely on the energy and nutrients derived both from photosymbiotic microbes and from filtered particulate food.

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“…Sharp peaks in the XRD spectra of these mixtures were attributed to crystalline quartz and the internal standard (α-alumina), but wider, more subdued peaks were observed around 20–30° 2θ, indicating amorphous material2122, in samples with smaller quartz contents (Supplementary Figure 2a). Most silicate minerals, such as feldspar, show similar broad bump in their amorphous state23.…”

Section: Methodological Proceduresmentioning

confidence: 98%

Preservation of amorphous ultrafine material: A proposed proxy for slip during recent earthquakes on active faults

Hirono

Asayama

Kaneki

et al. 2016

Sci Rep

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The criteria for designating an “Active Fault” not only are important for understanding regional tectonics, but also are a paramount issue for assessing the earthquake risk of faults that are near important structures such as nuclear power plants. Here we propose a proxy, based on the preservation of amorphous ultrafine particles, to assess fault activity within the last millennium. X-ray diffraction data and electron microscope observations of samples from an active fault demonstrated the preservation of large amounts of amorphous ultrafine particles in two slip zones that last ruptured in 1596 and 1999, respectively. A chemical kinetic evaluation of the dissolution process indicated that such particles could survive for centuries, which is consistent with the observations. Thus, preservation of amorphous ultrafine particles in a fault may be valuable for assessing the fault’s latest activity, aiding efforts to evaluate faults that may damage critical facilities in tectonically active zones.

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Microstructure of selected aggregate quartz by XRD, and a critical review of the crystallinity index

Cited by 52 publications

References 18 publications

Silicon Dioxide (SiO2) Is the Most Important Component of Spots on the Inner Surface of Mactra veneriformis Shells

Silicon Dioxide (SiO2) Is the Most Important Component of Spots on the Inner Surface of Mactra veneriformis Shells

The giants of the phylum Brachiopoda: a matter of diet?

Preservation of amorphous ultrafine material: A proposed proxy for slip during recent earthquakes on active faults

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