Micaceous Clay Research Articles

DNA and the origins of life in micaceous clay

Reproducible imaging of DNA by atomic force microscopy was a useful predecessor to Ned Seeman’s DNA nanotechnology. Many of the products of DNA nanotechnology were imaged in the atomic force microscope. The mica substrate used in this atomic force microscopy research formed the inspiration for the hypothesis that micaceous clay was a likely habitat for the origins of life. Montmorillonite clay has been a successful substrate for the polymerization of amino acids and nucleotides into peptides and DNA oligomers in research on life’s origins. Mica and montmorillonite have the same anionic lattice, with a hexagonal spacing of 0.5 nm. Micas are nonswelling clays, with potassium ions (K+) holding the crystal sheets together, providing a stable environment for the processes and molecular complexes needed for the emergence of living cells. Montmorillonite crystal sheets are held together by smaller sodium ions (Na+), which results in swelling and shrinking during wet-dry cycles, providing a less stable environment. Also, the cells in all types of living systems have high intracellular K+ concentrations, which makes mica a more likely habitat for the origins of life than montmorillonite. Finally, moving mica sheets provides mechanical energy at the split edges of the sheets in mica “books.” This mechanical energy of mica sheets, moving open and shut, in response to fluid flow, may have preceded chemical energy at life’s origins, powering early prebiotic processes, such as the formation of covalent bonds, the interactions of molecular complexes, and the budding off of protocells before the molecular mechanism of cell division had developed.

Potassium at the Origins of Life: Did Biology Emerge from Biotite in Micaceous Clay?

Intracellular potassium concentrations, [K+], are high in all types of living cells, but the origins of this K+ are unknown. The simplest hypothesis is that life emerged in an environment that was high in K+. One such environment is the spaces between the sheets of the clay mineral mica. The best mica for life’s origins is the black mica, biotite, because it has a high content of Mg++ and because it has iron in various oxidation states. Life also has many of the characteristics of the environment between mica sheets, giving further support for the possibility that mica was the substrate on and within which life emerged. Here, a scenario for life’s origins is presented, in which the necessary processes and components for life arise in niches between mica sheets; vesicle membranes encapsulate these processes and components; the resulting vesicles fuse, forming protocells; and eventually, all of the necessary components and processes are encapsulated within individual cells, some of which survive to seed the early Earth with life. This paper presents three new foci for the hypothesis of life’s origins between mica sheets: (1) that potassium is essential for life’s origins on Earth; (2) that biotite mica has advantages over muscovite mica; and (3) that micaceous clay is a better environment than isolated mica for life’s origins.

Potassium from micaceous clay for the origins of life

This hypothesis for the origins of life includes recent research results in areas such as Liquid-Liquid Phase Separation by Brangwynne and many others, mechanochemistry in biological systems, and the polymerization of nucleotide monophosphates on mica by Hassenkam, Damer, Mednick, and Deamer [2020]. According to this origins hypothesis, mica in micaceous clay provided an ideal environment for emerging life (1-4). Life also imitates mica in many ways. One similarity between life and mica is the presence of high concentrations of potassium ions, K+.

Receiving Composite Sorbents for Sewage Treatment on the Basis of Waste of Production and Processing of Micaceous Quartzite

The results of a research of a way of receiving a composite sorbent with the use of waste of production and processing of the micaceous quartzites (MQ) and montmorillonite clays (MC) are given in this work. The structure of composite sorbents was caused by aspiration as much as possible, to use positive properties of all components entering composition: their high sorption, knitting and plasticizing properties. Similar approach to a combination of components gives, as a result, a synergetic effect, allows to receive the highly effective and, at the same time, inexpensive, rather universal materials having high sorption properties. The sorption activity is investigated, the efficiency of natural and composite sorbents is defined, the increase in sorption activity, depending on structure of composition and temperature of preliminary preparation of a sorbent, is proved. Application of the offered composite sorbents will allow to solve in a complex the existing ecological problems: to carry out effective purification of industrial sewage, first of all, machine-building enterprises from ions of heavy metals, and to utilize waste of production and processing of micaceous quartz.

Selective removal of radiocesium from micaceous clay for post-accident soil decontamination by temperature-controlled Mg-leaching in a column

The effective and efficient removal of radioactive Cs from contaminated soil is highly urgent for the nuclear post-accident remediation. In present study, we achieved rapid Cs desorption from both a typical micaceous clay (i.e., vermiculitized biotite, VB) and actually contaminated soil by high-speed ion exchange through temperature-controlled continuous leaching with Mg-solutions in a column reactor. Cs-sorbed VB was firstly employed as a soil surrogate to explore the macro-Cs desorption process and micro-mechanism in detail. Results showed that VB sandwiched the adsorbed Cs to its interlayers within collapsed structure (10.7 Å) and prevent Cs release even by abundant extraction with H2O at 250 °C or Mg2+ at 25 °C. However, Mg2+-extracted Cs desorption boosted significantly with elevating temperatures and 100 % of sorbed-Cs was removed from Cs-VB leached above 150 °C. Further structural and composition analysis of the leached specimen ensured that solvated Mg2+ preferentially entered into Cs+-collapsed interlayers at 150 °C than K+-interlayers above 200 °C, leading to prior complete Cs removal over K from VB at lower temperatures. By contrast, the Cs-contaminated soil reduced by ∼39 % but ∼82 % of its initial radioactivity after equally leaching with same volumes of Mg2+-solution at 150 and 200 °C, respectively. These temperature-controlled Cs desorption validated that radioactive Cs in actual soil indeed be tightly trapped by micaceous clays nearly in the Cs-K co-collapsed interlayers, to which its extraction by other cations can conditionally occur above enough high leaching temperatures. These superior features would inspire new insights for the design of novel practical technologies for treatment and decontamination of the nuclear post-accident soils.

Mechanical behavior of micaceous clays

This study aims to investigate the effect of mica content on the mechanical properties of clays. Commercially available ground mica was blended with a locally available clayey soil, at varying mica contents by mass of 5%, 10%, 15%, 20%, 25% and 30%, to artificially prepare various micaceous clay blends. The preliminary testing phase included consistency limits and standard Proctor compaction tests. The primary testing program consisted of unconfined compression (UC), direct shear (DS) and scanning electron microscopy (SEM) tests. The test results showed that the liquid and plastic limits exhibited a linear, monotonically increasing trend with increase in mica content. The rate of increase in the plastic limit, however, was found to be greater than that of the liquid limit, thereby leading to a gradual transition towards a non-plastic, cohesionless character. The soft, spongy fabric and high water demand of the mica mineral led to higher optimum water contents and lower maximum dry unit weights with increasing mica content. Under low confinement conditions, i.e. the UC test and the DS test at low normal stresses, the shear strength was adversely affected by mica. However, the closer packing of the clay and mica components in the matrix under high confinement conditions offsets the adverse effects of mica by inducing frictional resistance at the shearing interface, thus leading to improved strength resistance.

Mechanical Performance of Jute Fiber-Reinforced Micaceous Clay Composites Treated with Ground-Granulated Blast-Furnace Slag.

The combined capacity of Jute Fibers (JF), the reinforcement, and Ground-Granulated Blast-Furnace Slag (GBFS), the binder, was examined as a sustainable solution towards ameliorating the inferior engineering properties of micaceous clays. A total of sixteen JF + GBFS mix designs, i.e., JF (% by total mass) = {0, 0.5, 1.0, 1.5} and GBFS (% by total mass) = {0, 3, 6, 9}, were tested for unconfined compression (UC) strength; for those mix designs containing GBFS, curing was allowed for 7 and 28 days prior to testing. Scanning electron microscopy (SEM) studies were also carried out to observe the evolution of fabric in response to JF, GBFS and JF + GBFS amendments. The greater the JF content the higher the developed strength and stiffness up to 1% JF, beyond of which the effect of JF-reinforcement led to some adverse results. The JF inclusions, however, consistently improved the ductility and toughness of the composite. The addition of GBFS to the JF-reinforced samples improved the soil–fiber connection interface, and thus led to further improvements in the composite’s strength, stiffness and toughness. The mix design “1% JF + 9% GBFS” managed to satisfy ASTM’s strength criterion and hence was deemed as the optimum choice in this investigation. Finally, a non-linear, multivariable regression model was developed and validated to quantify the peak UC strength as a function of the composite’s index properties. The proposed model contained a limited number of fitting parameters, all of which can be calibrated by little experimental effort, and thus implemented for preliminary design assessments.

Effects of radiocesium fixation potentials on 137Cs retention in volcanic soil profiles of Fukushima forests

Radiocesium is well-known to be stabilized by clay minerals in soils, while volcanic soils could typically be poor in micaceous clays that fix 137Cs effectively. We investigated 137Cs fixation potentials [radiocesium interception potential (RIP)] and depth distribution of 137Cs stocks in volcanic soils to analyze effects of clay content and mineralogy on soil retention and migration of 137Cs after the Fukushima nuclear accident. Clay minerals of the volcanic soils were dominated by hydroxy-interlayered vermiculite (HIV) and short-range-order minerals, irrespective of bedrocks. The soil RIPs were positively correlated with mass of clay fraction among the HIV-dominated volcanic soils, but RIP per clay content in the HIV-dominated volcanic soils were lower than in the soils rich in illite or vermiculitic clays. The small RIPs in the organic horizons resulted in rapid 137Cs migration from the organic horizons and their accumulation in the upper 0–5 cm mineral soil. Although RIPs of the studied volcanic soils fall within the lower class among major soil types, vertical 137Cs migration in the mineral soil is small unless RIP is less than 300–400 mmol kg−1 due to the low clay contents and shortage of illite or vermiculite.

Eastern Sigillata at Sardis: Evidence for a Local Industry

Eastern Sigillata B was an important ceramic ware of the Early Roman East, characterized by a shiny red gloss, micaceous clay body, and, in its first phase, epigraphic stamps on the vessel floor. Production was established in the Great Meander Valley in western Asia Minor as an offshoot of the Italian sigillata industry and flourished primarily in the 1st and 2nd centuries c.e. Vessels excavated at Sardis, some 75 km to the northeast, share the micaceous clay and red gloss of Eastern Sigillata B and are visually almost identical to products of the main production center, but some bear name stamps unique to the site, suggesting that a local production center existed at Sardis. It is now possible to test this proposal through wavelength dispersive X-ray fluorescence analysis and, on this basis, to identify a group of local products. This article describes that process, sketches a portrait of local production, and explores the mechanism and timing of its establishment at Sardis.

A structural coarse-grained model for clays using simple iterative Boltzmann inversion.

Cesium-137 is a major byproduct of nuclear energy generation and is environmentally threatening due to its long half-life and affinity for naturally occurring micaceous clays. Recent experimental observations of illite and phlogopite mica indicate that Cs+ is capable of exchanging with K+ bound in the anhydrous interlayers of layered silicates, forming sharp exchange fronts, leading to interstratification of Cs- and K-illite. We present here a coarse-grained (CG) model of the anhydrous illite interlayer developed using iterative Boltzmann inversion that qualitatively and quantitatively reproduces features of a previously proposed feedback mechanism of ion exchange. The CG model represents a 70-fold speedup over all-atom models of clay systems and predicts interlayer expansion for K-illite near ion exchange fronts. Contrary to the longstanding theory that ion exchange in a neighboring layer increases the binding of K in lattice counterion sites leading to interstratification, we find that the presence of neighboring exchanged layers leads to short-range structural relaxations that increase basal spacing and decrease cohesion of the neighboring K-illite layers. We also provide evidence that the formation of alternating Cs- and K-illite interlayers (i.e., ordered interstratification) is both thermodynamically and mechanically favorable compared to exchange in adjacent interlayers.

The mineralogy and firing behaviour of pottery clays of the Lake Van region, eastern Turkey

AbstractThe present study focused on the mineralogical and chemical characterization and firing behaviour of clays from the Lake Van region and compared them with the same characteristics established for two ancient pot sherds. Four pottery clays collected from Kutki and Kuşluk in the Kesan Valley to the south, from Kavakbaşı to the southwest and from Bardakçı village on the east coast of Lake Van were analysed by X-ray diffraction to identify mineralogical composition (bulk clays and <2 μm fractions after heating at 300–500°C and ethylene glycol solvation). Further analyses were conducted to determine the size distribution, chemical composition and physical properties of test bodies derived from these clays. The in situ weathered schist forming the primary micaceous red clays which are suitable for local pottery production are characterized by large muscovite-sericite-illite and small calcite contents. In contrast, the Bardakçı clays are dominated by large smectite contents and are only used sparingly in mixtures of local pottery production because they undergo firing shrinkage and present drying and firing flaws in the fired bodies. Firing ranges of ~800–900°C were inferred from the mineralogy and colours of the two ancient sherds from Kutki. As a result of mineralogical analysis of fired and unfired test bodies of these pottery clays and pot sherds, two different types of pastes were determined for pottery production in the Lake Van region: metamorphic and volcanic paste, the former characterized by a calcite-poor and mica-sericite-rich matrix and the latter by large smectite and small calcite contents.

Direct Exchange Mechanism for Interlayer Ions in Non-Swelling Clays.

The mobility of radiocesium in the environment is largely mediated by cation exchange in micaceous clays, in particular Illite-a non-swelling clay mineral that naturally contains interlayer K+ and has high affinity for Cs+. Although exchange of interlayer K+ for Cs+ is nearly thermodynamically nonselective, recent experiments show that direct, anhydrous Cs+-K+ exchange is kinetically viable and leads to the formation of phase-separated interlayers through a mechanism that remains unclear. Here, using classical atomistic simulations and density functional theory calculations, we identify a molecular-scale positive feedback mechanism in which exchange of the larger Cs+ for the smaller K+ significantly lowers the migration barrier of neighboring K+, allowing exchange to propagate rapidly once initiated at the clay edge. Barrier lowering upon slight increase in layer spacing (∼0.7 Å) during Cs+ exchange is an example of "chemical-mechanical coupling" that likely explains the observed sharp exchange fronts leading to interstratification. Interestingly, we find that these features are thermodynamically favored even in the absence of a heterogeneous layer charge distribution.

Mechanism of Strong Affinity of Clay Minerals to Radioactive Cesium: First-Principles Calculation Study for Adsorption of Cesium at Frayed Edge Sites in Muscovite

The present first-principles study based on density-functional theory confirms that frayed edge sites (FESs) formed in micaceous clays have a crucial role in the long-term stability of radioisotopes of Cs on the topsoil surface. An FES is modeled according to the weathering scenario of muscovite, and the substitution of originally occupied K with Cs is virtually simulated. The calculation results clearly demonstrate that such a replacement is strongly promoted only when the stack structure is loosely expanded at the clay edges. This is the first atomic-scale confirmation of the strong affinity of FESs to Cs, which may shed new light on the decontamination engineering of soil materials.

Movement behaviour of the Little Chief Slide

The Little Chief Slide has been extremely slow moving at a rate of 4–14 mm/year since the late 1960s. The 800 million m3slide lies about 3 km upstream of Mica Dam in British Columbia. The extremely slow rate was not affected by the Mica Dam reservoir filling in the 1970s. Although the Little Chief Slide is classified as a rock slide, the extremely slow movements take place on seams of soft materials composed mainly of micaceous clay gouge. The characteristics of the movement trends with time were investigated at six zones using in-place inclinometers (IPIs). The trends of the movement with the reservoir level fluctuations and pore pressure changes were investigated to quantify the contribution of steady-state creep to the total in situ movements. The creep behaviour of the clay gouge materials forming the movement zones was also investigated in the laboratory. The laboratory and field creep behaviours were then compared. The movement could be partitioned into steady-state creep and seasonally induced creep movements. This partitioning identified the locations where the seasonal movements are the highest, and, hence, where drainage measures could have the biggest impact.

Dielectric properties of micaceous clays determined by terahertz time-domain spectroscopy

Micaceous layered clay minerals, as utilized in many electro-technical applications, were studied by terahertz time-domain spectroscopy (THz-TDS). The dielectric behavior of clay samples was investigated in a far-infrared region of 0.8 and 6.0 THz corresponding to ∼27 to 200 cm–1, respectively. The samples were also characterized by X-ray diffraction and Fourier transform infrared spectroscopy, and chemical analysis by energy dispersive X-ray spectroscopy. Muscovite with dehydrated K+ interlayer cations was compared with vermiculite having hydrated Mg2+ interlayer cations. The frequency dependence of complex index of refraction varied between 2.43 and 2.48 for muscovite and from 2.23 to 2.08 for vermiculite. The frequency dependence of the power absorption coefficient revealed clear absorption bands for muscovite at 1.95 THz (65 cm−1) and 4.60 THz (153.4 cm−1), and asymmetric band at 2.5 THz (83.4 cm−1) for vermiculite. The band positions were compared with far infrared Fourier transform spectroscopic results achieved by conventional techniques. The differences found were attributed to variations in chemical composition and the stacking order of the micaceous clays used.

Selective leaching studies of sediments from a seamount flank in the Central Indian Basin: Resolving hydrothermal, volcanogenic and terrigenous sources using major, trace and rare-earth elements

We have investigated the sediments from a site where a newly discovered submarine hydrothermal alteration of recent origin is located to identify the source components and estimate their relative contribution. The site is situated on the flank of a seamount in the Central Indian Basin along the 76° 30′ E fracture zone which traces the movement of the Rodriguez triple junction. Detailed analyses of major, trace and rare earth elements (REE) on the bulk, leach, residue and clay fraction, and infra red spectroscopy studies of the clay fraction helped characterize the hydrothermal nature of the sediments. Selective dissolution carried out using HCl has allowed the discrimination between a leach phase (leachable Fe–Mn oxide) and a residue phase (refractory). The sediments are iron-rich, majority of Fe, Mn is in leachable fraction and are compositionally comparable to ridge-crest metalliferous sediments. Elemental ratios and geochemical discrimination plots of major element data reveal that the sediments are a mixture of Fe-rich mineral phases on one hand apparently from hydrothermal sources and aluminosilicates such as illite, zeolites, micaceous clays and smectites contributed from the Bengal fan, weathering of basinal basalts and authigenic processes. Ternary mixing calculations of bulk sediment major element data show that 35–45% metalliferous sediments could reproduce Fe and Mn values of our sediments. The shale normalized REE patterns of the bulk sediments are remarkably similar to those of the HCl soluble leach fraction, implying that the REEs in the HCl soluble leach fraction dominate the bulk fraction. HCl leacheates exhibit characteristics of vent fluids as well as seawater with pronounced Eu anomaly with HREE enrichment and negative Ce anomaly. The residue on the other hand has a high concentration of Fe, V, Zn, and Pb indicating a sulfidic input to the sediments. Ternary mixing calculations of REEs carried out on the residual fraction indicate that the sulfide-like material dominates (64–72%) over terrigenous (10–20%) and MORB derived (16–18%) components. This study helped us identify and quantify two types of hydrothermal material in the sediments, dominated by Fe–Mn phases (ferruginous oxides and silicates; Mn-oxides) in leachable fraction and sulfide-like material in residual phases. The clay fraction is mainly composed of dioctahedral smectites and has a composition similar to Alvin nontronite. The geochemical and mineralogical characteristics collectively suggest that these sediment-hosted precipitates formed at relatively low temperatures ranging between 50 and 100 °C from a mixture of seawater and hydrothermal fluids. The presence of hydrothermal sediments in the vicinity of a fracture zone suggests the occurrence of localized hydrothermal activity associated with intra plate volcanism. This is probably induced by reactivation of tectonic forces along the fracture zones.

Clay mineralogy, organic carbon burial, and redox evolution in Proterozoic oceans

Clay minerals formed through chemical weathering have long been implicated in the burial of organic matter (OM), but because diagenesis and metamorphism commonly obscure the signature of weathering-derived clays in Precambrian rocks, clay mineralogy and its role in OM burial through much of geologic time remains incompletely understood. Here we have analyzed the mineralogy, geochemistry and total organic carbon (TOC) of organic rich shales deposited in late Archean to early Cambrian sedimentary basins. Across all samples we have quantified the contribution of 1 M and 1 M d illite polytypes, clay minerals formed by diagenetic transformation of smectite and/or kaolinite-rich weathering products. This mineralogical signal, together with corrected paleo-weathering indices, indicates that late Archean and Mesoproterozoic samples were moderately to intensely weathered. However, in late Neoproterozoic basins, 2 M 1 illite/mica dominates clay mineralogy and paleo-weathering indices sharply decrease, consistent with an influx of chemically immature and relatively unweathered sediment. A late Neoproterozoic switch to micaceous clays is inconsistent with hypotheses for oxygen history that require an increased flux of weathering-derived clays (i.e., smectite or kaolinite) across the Precambrian–Cambrian boundary. Compared to previous studies, our XRD data display the same variation in Schultz Ratio across the late Neoproterozoic, but we show the cause to be micaceous clay and not pedogenic clay; paleo-weathering signals cannot be recovered from bulk mineralogy without this distinction. We find little evidence to support a link between these mineralogical variations and organic carbon in our samples and conclude that modal clay mineralogy cannot by itself explain an Ediacaran increase in atmospheric oxygen driven by enhanced OM burial.

SANGRE DE CRISTO MICACEOUS CLAYS

Archaeological research has shown that northern Rio Grande potters have used micaceous clays in the production of cooking, serving, and ritual vessels for more than 700 years, yet little is known about the raw material sources used to make these remarkable wares. Recent survey with traditional potters reveals the locations of micaceous clay deposits and the criteria used to select clays for pottery manufacturing. Instmmental neutron activation analysis (INAA) of raw material samples demonstrates that sources are chemically distinct and that archaeological and ethnographic vessels may be matched to them with a high degree of confidence. Source matches for ceramics attributed to Pueblo, Jicarilla Apache, and Hispanic potters illustrates the potential of geochemical testing to reveal previously unrecognized complexity in the ceramic markets and land-use patterns of the northern Rio Grande. A case study from Picurís Pueblo showcases the relevance of ceramic source analysis to modern pottery communities.

Rhizosphere Effects on Cesium Fixation Sites of Soil Containing Micaceous Clays

Physical and chemical weathering processes in the rhizosphere may lead to the generation of a greater density of Cs‐selective frayed edge sites (FES) on rhizosphere soil as compared with bulk soil. This study was undertaken to determine if there are significant differences between bulk and rhizosphere soils from the Idaho National Laboratory (INL) with respect to their ability to bind Cs. The capacity of FES on bulk and rhizosphere soil materials and conditional Cs/K selectivity of FES cKexFES were determined as a function of both soil type and initial exchanger composition. The FES capacity was significantly higher in untreated, Ca‐saturated, and K‐saturated rhizosphere soil materials as compared with bulk soil materials. Sorption–desorption isotherms were obtained at Cs concentrations between 5 × 10−9 and 5 × 10−6 M No difference in Cs sorption was observed between bulk and rhizosphere soil materials. The composition of the exchanging solution had the greatest effect on the magnitude of Cs desorption; significantly more Cs was desorbed in the presence of KCl than in either CaCl2 or a mixed‐cation soil solution. In addition, Cs desorption was greater from rhizosphere soil materials relative to bulk soil materials. Cesium selectivity with respect to both Ca and K was significantly suppressed by weathering in the rhizosphere. We conclude that enhanced weathering in the rhizosphere increased the Cs sorption capacity of FES, but also reduced Cs selectivity on these sites. Enhanced Cs desorption from rhizosphere INL soils is likely in the presence of actively growing plants and associated microorganisms.

Thermal behaviour and characterization of an iron aluminum arsenate mineral

It has been determined the thermal behaviour at high temperatures of an iron aluminum arsenate mineral first described in the location of La Serena Valley, Extremadura, Spain, which expands until 1173 K contracting later and softening at 1653 K and full melting at 1773 K. The DTA/TG experiment only detects some rearrangement with an endothermic at 1173 K due to the mica mixing. The mineral is a scorodite variety mixed with micaceous clay which has been found as aggregates of pyramidal crystals associated with quartz, wolframite, molibdenite, cassiterite and other secondary minerals in the pegmatite of the San Nicolas mine. The chemical composition, the physico- chemical characteristics such as density and hardness, as well as the thermal behaviour has allowed to conclude that this mineral can be an Al-enriched scorodite (mansfieldite): (Fe, Al) AsO4·2H2O mixed with illite from the scorodite-mansfieldite series.