A new model is proposed for analysis of the source clays used to create ceramics, based on geographic, petrographic, mineralogical, mineral-chemistry, and geochemical criteria. The development of this model became feasible after the discovery of a Pliocene volcanic clay horizon on NWAegina Island, Greece. The volcanic clay contains smectite, mixed-layer chlorite-smectite, biotite, and palygorskite and has greater feldspar content than the underlying Pliocene marls, which contain R0 mixed-layer illitesmectite, mica, dolomite, serpentine, talc and gypsum, and, in some places, palygorskite. The two units have distinct geochemical characteristics. In general the Pliocene volcanic clay is richer in SiO2, Al3O3, and Fe2O3 and poorer in Na2O, MgO, and P2O2 than the Pliocene marls. The Nb, Zr, Hf, Th, and rare earth element (REE) contents are also significantly greater in the Pliocene volcanic clay and comparable to those of the dacitic rocks of the island, reflecting the volcanic origin of the clay.

The proposed model was used to identify the source-clay materials that were used for the production of ceramics on the island of Aegina (Aeginetan Ware). All five criteria should be considered in any provenance study. The use of individual criteria on their own can lead to ambiguous conclusions. In the present study the geochemical criterion was particularly helpful. It provided robust evidence for the nature of the source clay. The Pliocene volcanic clay horizon and the underlying Pliocene marls are the candidate raw materials for Aeginetan Ware. Although the Pliocene marls have been invoked as raw materials for Greek Bronze Age (~3000–1100 BC) Aeginetan ceramics and are used as raw materials by modern Aeginetan ceramists, the geochemical characteristics of a large set of Bronze Age Greek Aeginetan sherds with fine and coarse fabrics coincide with those of the Pliocene volcanic clay. This comparative and cumulative evidence suggests that the Pliocene volcanic clay was the main source clay for ancient Aeginetan ceramics, regardless of the fabric (coarse or fine) and that admixture of different sources might not be necessary for fine-grained ceramics.

The geochemistry of minerals in intermediate to deep sedimentary rocks (2–10 km depth) is not known sufficiently well to predict accurately the effect of human activities, such as carbon dioxide sequestration or fracking. To carry out real-time experiments, a high-pressure environmental chamber (HPEC) was constructed for in situ X-ray diffraction (XRD) studies to 1000 bars and to 200°C. In the HPEC, a liquid, e.g. a brine, plus sample in suspension, is pressurized by gas, e.g. CH4 or CO2, or liquid, e.g. supercritical CO2. The unique aspect of this chamber is that the sample + liquid (~2 mL) form a dynamic system, and particles can move freely in the liquid while being illuminated by the X-ray beam. Several HPECs were constructed of Ti alloy, stainless steel, or carbon-fiber polyether ketone to be resistant to corrosion under basic or acidic conditions. These HPECs are compatible with standard transmission-mode diffractometers with sealed-tube X-ray sources (Mo radiation is being used at the University of Illinois at Chicago — UIC) or with brilliant X-ray sources. In addition, to allow long-duration studies or, for example, to study the effect of micro-organisms on these mineral reactions, a large-bore (~25 mL) reaction vessel system was devised that could be examined regularly at appropriate P/T conditions or off-line. Calibration of the HPEC and XRD pattern processing is discussed and illustrated. The potential significance of these devices goes beyond understanding the deep sedimentary environment, because materials and reactions can be studied while using nearly any liquid as an immersion agent. As an example, experimental results are given for the d001 values of montmorillonite clay vs. temperatures to 150°C at P(CO2) = 500 bars in a NaCl-rich brine.

The Güzelyurt kaolinite deposit is an important source of raw material for the ceramics industry in Turkey. No detailed mineralogical or geochemical characterizations of this deposit have been undertaken previously and these were the goals of the present study. The Güzelyurt alunite-bearing kaolinite occurs along a fault zone in the Late Miocene Gödeles ignimbrite, which consists of dacitic and andesitic tuffs. Horizontal and vertical mineralogical zonations with gradual transitions were observed within the alteration zone. The inner kaolinite, alunite, and 7 Å halloysite zones progress horizontally outward to a smectite zone; and native sulfur- and cinnabar-bearing alunite with 7 Å halloysite and porous silica zones increase as one progresses up through the profile. Fe-(oxyhydr)oxide phases associated with native sulfur and cinnabar demonstrate that multiple hydrothermal-alteration processes resulted in kaolinization and alunitization of the deposit. The kaolinization of feldspar, Fe-(oxyhydr)oxidation of hornblende and mica, the presence of kaolinite as stacked and, locally, book-like forms, and of 7 Å halloysite tubes, and smectite flakes as a blanket on altered volcanic relicts indicate an authigenic origin for this deposit. The leaching of Si + Mg + K and Ba + Rb, the retention of Sr, the enrichment of light rare earth elements relative to the heavy rare earth elements, and the negative Eu anomalies suggest that fractionation of plagioclase and hornblende occurred within the volcanics. The oxygen- and hydrogen-isotopic values of the kaolinite, 7 Å halloysite, smectite, and smectite + kaolinite fractions reflect a steam-heated environment at temperatures in excess of 100°C. An increase in the δD and δ18O values of 7 Å halloysite relative to kaolinite suggests its formation under steam-heated magmatic water, the mixing of steam and meteoric water near the surface, and evaporation. The oxygen- and sulfur-isotopic compositions of alunite suggest the direct influence of steam-derived sulfur. The Güzelyurt alunite-bearing kaolinite deposit is inferred to have formed after an increase in the (Al±Fe)/Si ratio and the leaching of alkali elements, which are driven by the sulfur-bearing low-temperature hydrothermal alteration of feldspar, hornblende, and volcanic glass under acidic conditions within the Neogene dacitic and andesitic tuffs.

Clays are used widely as facial masks to remove excess sebum, an oily substance released onto the skin. Smectite, illite, kaolinite, and in some cases, chlorite, are the dominant phyllosilicates in most commonly used clay facial masks. To date, the adsorption of human sebum has been proved only on smectite clays; in the present study the adsorption of two organic compounds found in human sebum by illitic, kaolinitic, and chloritic phyllosilicates was investigated. Illitic clays are often used in cosmetic clay masks, but usually contain some fine-grained non-clay minerals. The presence of carbonate, for example, can cause skin irritation because of its alkaline nature, and iron oxides and hydroxides reduce the adsorption properties of clays. The influence of the removal of these compounds on the adsorption properties of illitic clays was also investigated. The amounts of both compounds adsorbed were established by UV-VIS spectrophotometry. All samples were characterized by mineralogical composition, particlesize distribution, specific surface area, and cation exchange capacity (CEC). Oleic acid and squalene were adsorbed on all clay samples, but illitic and chloritic phyllosilicates showed the greatest adsorption capacity. After purification, the sizes of the particles decreased and the CEC values increased. Nevertheless, the dissolution of carbonates essentially had no influence on the adsorption properties, whereas the removal of iron oxides and hydroxides increased significantly the amounts adsorbed of both oleic acid and squalene.

The benefits of using kaolin as a source of aluminosilicate in zeolite synthesis to obtain lowercost catalysts, adsorbents, or ion exchangers are widely known. Previous attempts to produce zeolite from natural Iranian kaolin resulted in the formation of zeolites A, X, and HS. Zeolite Y plays an important role in the petrochemical industry due to its application in the area of fluidized catalytic cracking; ~40% of gasoline production is obtained using this process.

In the present study, different methods were used to prepare pure zeolite NaY from the Iranian kaolin available. The effects of different parameters such as aging time, crystallization time, kaolin calcination and crystallization temperature, and starting-material composition were investigated in order to obtain improved properties and maximize phase purity. In all cases, the crystal structure and microstructure were studied using X-ray diffraction and scanning electron microscopy. Among different synthesis approaches, the ‘guide-agent method’ resulted in the formation of zeolite NaY. The synthesis was generally sensitive to changes in kaolin calcination temperature and in hydrothermal synthesis parameters. The optimum parameters to prepare pure zeolite NaY were: kaolin calcination temperature = 680°C, aging time of guide agent = 48 h without an overall gel aging step, and crystallization at 90°C for 36 h.