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The x-ray identification and crystal structures of clay minerals
01 Jan 1961-
About: The article was published on 1961-01-01 and is currently open access. It has received 966 citations till now. The article focuses on the topics: Clay minerals.
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TL;DR: In this paper, the rate of dissolution of Fe in 1M HCl followed the cube root equation with a single straight line describing the data, however for samples where both goethite and hematite were present the data did not conform to this equation.
64 citations
TL;DR: In this paper, a classification scheme was devised which relates variation of clay mineralogy to diagenetic stages and burial depth, based on a combination of criteria and data derived from the studies of Weaver (1961a), Kubler (1966), Burst (1969) and Dunoyer de Seconzac (1970), the upper and middle parts of the formation (upper 3250 ft) fall within the middle stage of diagenesis whereas the lower part (1000 It) is allocated to the beginning of late diagenisation.
Abstract: Clay minerals from shale outcrops of the Lower Cretaceous Buckinghorse Formation (4250 fl thick) were investigated in order to assess their degree of diagenesis and their oil-generating potential. Crystallinity index, sharpness ratio, per cent of illite which is the 2M polymorph and presence of discrete minerals have been studied in the whole clay fraction, while the very fine clay fraction has been subjected to X-ray diffraction, differential thermal, thermogravimetric, differential thermogravimetric, i.r. spectros- copy, surface area and chemical analyses. With information derived from these studies and from published data, a classification scheme was devised which relates variation of clay mineralogy to diagenetic stages and burial depth. Data on the < 2 #m size fraction show that the crystallinity index decreases while the sharpness ratio and per cent of illite which is the 2M polymorph increase with burial depth. Results on the <0.08/zm fraction reveal that a three-component interstratified clay mineral exists. In addition, Fourier transform calcula- tions and chemical and physicochemical analyses indicate that both the ratio of the amounts of non- hydrated clays (illite) to hydrated clays and the K2O content of clays increase with burial depth: cation exchange capacity and surface area decrease with burial depth. Based upon a classification scheme, which was devised by combining criteria and data derived from the studies of Weaver (1961a), Kubler (1966), Burst (1969)and Dunoyer de Seconzac (1970), the upper and middle parts of the formation (upper 3250 ft) fall within the middle stage of diagenesis whereas the lower part (1000 It) is allocated to the beginning of late diagenesis. In terms of Burst's (1969) work, the upper 3250 ft are transitional between the stability and dehydration zones indicating that, prior to uplift, hydrocarbons may have been in the process of migration. The lower 10000 ft of the formation are in the restricted dehydration zone, indicating that hydrocarbon migration should have been completed.
64 citations
01 Jul 2006
TL;DR: In this paper, the microstructural behavior of Singapore marine clay was examined using X-ray diffraction, scanning electron microscopy, (SEM) mercury intrusion porosimetry and laser diffractometric measurement of particle size distribution.
Abstract: This paper examines the microstructural behaviour of cement-treated soft Singapore marine clay. The microstructure was investigated using X-ray diffraction, (XRD) scanning electron microscopy, (SEM) mercury intrusion porosimetry, and laser diffractometric measurement of particle size distribution. The XRD analysis of cement-treated clay enables the identification of the formation of cementitious products, namely calcium silicate hydrate (CSH) and calcium aluminium silicate hydrate (CASH). The relative amount of cementitious products (CSH + CASH) is found to increase with increase of the cement content. The fabric of the treated clay changes to flocculated type, comprising clay-cement clusters separated by large intercluster voids with smaller intra-cluster pores, as can be seen from the SEM images of treated clay. This change is more pronounced with higher cement content and prolonged curing time. The flocculation of the clay particles also causes water to be trapped within the clay-cement cluster and inc...
63 citations
Cites methods from "The x-ray identification and crysta..."
...Mineralogical analysis from the X-ray diffraction pattern of the untreated clay was carried out based on the characteristics of Bragg’s angle from Brown (1961) and Mitchell (1992)....
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TL;DR: In this paper, it was shown that reaction with water vapour at 150-250 °C results in rapid irreversible loss of most of the swelling capacity, which causes very large increases in permeability of sand-bentonite mixtures.
Abstract: Sodic bentonite is widely used for industrial and scientific purposes, especially as a sealing agent1, because of its great ability to swell in water2,3. It has been proposed for use in high-level nuclear waste repositories as an impermeable barrier surrounding the waste package, or to fill tunnels, shafts and rooms. In some repositories, such as those planned in basalt, bentonite would be expected to be subjected to temperatures possibly up to 300 °C (refs 4, 5). As the waste would be approximately 600–900 m below the water table in fractured rock, the repository is expected to fill first with steam and then with liquid water4,6. Reaction of bentonite with liquid water produces a minimal loss of swelling capacity, but I show here that reaction with water vapour at 150–250 °C results in rapid irreversible loss of most of the swelling capacity. This causes very large increases in permeability of sand–bentonite mixtures7, thereby reducing the ability of a bentonite barrier to retard the flow of groundwater in proposed high-level nuclear waste repositories.
63 citations
TL;DR: In this paper, the physical and chemical properties of the Abiod limestone were analyzed using different techniques, such as XRF, XRD, FTIR and TG/DTA.
Abstract: Limestone beds of the Late Cretaceous Abiod formation (Campanian-Maastrichtian system) are fundamentally important for the economic growth of the raw material sector in Tunisia. However, little attention has been paid to the detailed physical and chemical properties of the Abiod limestone. Nine limestone samples collected from the Abiod formation outcropping in the areas of Bizerte, Gafsa and Gabes, Tunisia, as well as their separated clay fractions, were characterized using different techniques, such as XRF, XRD, FTIR and TG/DTA. XRF showed the chemical composition of the limestone in which calcium carbonate was the main constituent, and silica, iron and magnesium were the impurities. XRD also confirmed the presence of small amounts of clay minerals and quartz along with sharp peaks of calcite. FTIR spectra indicated that the limestone was mainly composed of CaCO3 in the form of calcite, as identified by its main characteristic absorption bands. These data were in agreement with XRD and XRF analysis data. The TG/DTA curves of the limestone samples, showing a close similarity to that of pure calcium carbonate, exhibited an endothermic peak between 600 and 760°C, with the maximum near 750°C. Moreover, FTIR spectra of clay fraction samples indicated high silica content in some samples. Especially the samples SD1 and SD2 collected in the northern area showed higher amounts of silica compared with those of AS1, AS2, CHB, ZNC, SND, MKM and GBS collected from southern districts. However, among the latter seven samples, one could recognize two groups based on the clay mineral investigations: (1) limestone with minor amounts of smectite and mixed layer minerals of smectite/illite (AS1 and 2, CHB, ZNC, SND and GBS) and (2) limestone with smectite, kaolinite and apatite (SND and MKM). Differences in these mineralogical and chemical characteristics should be considered when limestone from the Abiod formation is utilized as a medium for heavy metal removal from wastewater.
62 citations