A number of variable charge montmorillonites were prepared. One portion of each sample was extracted with ammonium chloride, while a second portion was first saturated with calcium chloride, washed, and then extracted with ammonium chloride. In both cases, the number of cations displaced by ammonium chloride was determined. The number of calcium ions displaced from Ca-saturated samples was higher than the sum of the number of lithium and calcium ions displaced from Li, Ca-mixed samples. The differences, increasing towards Li-rich end of the series are assumed to be due to protons liberated from the reaction of lithium ions with either structural hydroxyl groups or residual water molecules, as has been shown by other investigators. Supplementary X-ray and i.r. data lend support to this idea.

In recent years, the traditional use of digital collections as surrogates for the physical has shifted to a paradigm of viewing collections as data suitable for computational use and novel research methods. The burgeoning collections as data movement is gaining momentum among galleries, libraries, archives, and museums (GLAM) worldwide. Strategic initiatives, experimentation, innovation, and inspirational learning are occurring as digital libraries and digital humanities progress and work to develop sustainable approaches for collections as data programs. What is the position of collections as data in an ever-changing information landscape of open access, linked data, and shared data of cultural heritage collections? What has the past decade brought to the field?

Nephelometric (light scattering) methods for the determination of Ca and Ba in the 0–30 ppm range, and their application to the estimation of the cation exchange capacity (±10%) of small (≤30 mg) samples of clay minerals, are described and evaluated.

An essential feature of the Fibonacci sequence (Fn): 1, 1, 2, 3, 5, 8, … is an explicit expression for its nth term Fn (Binet’s formula) and the corollary that is the golden ratio and {x} is the nearest integer to x.

Possible assignments are suggested for some of the absorption bands in the 1150–400 cm−1 region of the i.r. spectra of serpentines. Polarized light was used to identify the out-of-plane vibrations in antigorites and platy lizardites and the vibrations parallel to the fibre axis in chrysotiles and fibrous lizardites. An attempt is made to correlate some known structural characteristics and the chemical composition of the serpentines with some features of the i.r. spectra.

Four chlorite polytypes of Bailey and Brown (1962) have been identified by X-ray diffraction in clay-size chlorites of soils, sediments, and sedimentary rocks: (1) IIb, the polytype of common metamorphic and igneous chlorites; (2) Ib(ß = 90°); (3) Ib(ß = 97°); (4) Ia. An additional stacking arrangement. Iba, is defined herein as disordered chlorite which lacks an h0l diffraction band in the 2.4–2.5 Å region.

Most type-I chlorites are authigenic, as demonstrated by thin-section petrography. Type-I chlorites form during diagenesis, or less commonly during halmyrolysis, at temperatures and pressures less than those of low-grade metamorphism. A type-1 crystallization sequence is proposed, from least to most stable: Iba → Ib(ß = 97°) → Ib(ß = 90°). Conditions of low-grade metamorphism usually are necessary to cause conversion of Iba(ß = 90°) to IIb, the most stable and common polytype. Chemical composition has little or no influence upon polytype relative stabilities; temperature is much more important.

Sediment source areas with high relief, abundant rainfall, cold climate, and which contain IIb-chlorite-bearing metamorphic rocks, may yield essentially unweathered IIb chlorite to sites of deposition. Thus, clay-size IIb chlorite in unmetamorphosed sedimentary rocks can be interpreted as detrital. Caution is required, however, because IIb may be able to form authigenically at submetamor-phic temperatures, because it is the most stable polytype. Petrographic evidence is useful in such cases.

Chlorite polytypism as a geothermometer can be applied to several geologic problems: (1) the authigenic versus detrital origin of clay minerals in sedimentary rocks, particularly in graywacke matrix; (2) the recognition of diagenetic facies or gradients, areally and stratigraphically, within given geologic provinces; (3) the detection of hydrothermal and incipient metamorphic effects. Chlorite polytypism merits general application as an interpretive tool.

The concept of tianxia (All-under-Heaven) has been described as a Chinese version of cosmopolitanism. However, tianxia is a hard-to-define term, with political, cultural, and geographic meanings. From the fifteenth century onwards, maps exist that claim to show tianxia, therefore allowing us to reconstruct how Chinese mapmakers understood tianxia’s geographic extent. Other terms in the titles of maps that show space beyond the borders of the Ming and Qing states include huayi (civilized and barbarian/Chinese and non-Chinese), wanguo (10,000 countries), and sihai (four seas). This article examines the geographic extent of these terms and changes in their usage between the fifteenth and eighteenth centuries. It argues that Ming Chinese mapmakers and scholars presented tianxia as equivalent to the Ming empire and used terms such as huayi and wanguo to advertise the maps as showing regions far away, like western Asia and the Americas. Jesuits in China, on the other hand, applied a broader meaning of tianxia, equating it with the whole globe. During the Qing, the extent of tianxia expanded to represent a cosmopolitan empire connected to a range of surrounding states, embedded in a wider world.

Tosudite was found in the Hokuno pottery stone mine, Gifu Prefecture, Japan. The pottery stone ore body, altered from the Cretaceous rhyolitic rock, is composed of tosudite, interstratified illite-montmorillonite, kaolinite and quartz. Prepared by normal sedimentation method, the specimen is composed of 75.6% tosudite, 24.0% kaolinite and 0.4% quartz. The chemical composition of the specimen is SiO2 45.09%, TiO2 tr., Al2O3 37.31%, Fe2O3 0.94%, MgO 0.41%, CaO 1.94%, Li2O 0.45%, Na2O 0.09%, K2O 0.44%, H2O(−) 1.50% and ignition loss 12.11%. After subtracting the compositions of the impurities, the structural formula of tosudite is given as; interlayer cations K0.23, Na0.07, Ca0.86 + nH2O; ‘gibbsite’ layer Li0.76, Mg0.35, ${\rm{Fe}}_{0.29}^{3 + }$, Al3.34 (OH)12.00; silicate layer Al8.00 [Si13.83 Al2.17] O40.00 (OH)8.00.

Syntheses of tosudite were made from a starting material which is an interstratified illite-montmorillonite obtained from the same ore body. At 450°C, 400atm., reacting for 5 days, a tosudite-like mineral was synthesized.

Chelating organic acids hampered the hydrolytic reactions of Al and affected the nature of the crystalline aluminum hydroxides. Chemical composition, structure, size, nature of functional groups, and concentration of each organic anion, as well as the pH of the system, controlled the rate of Al(OH)3 crystallization. The order of effectiveness of the various acids was: glutaric < succinic = phthalic < glycine < malonic < glutamic < aspartic < oxalic < salicylic = malic < citric < tartaric. An increase in the stability of complexes formed between the organic ligands and Al decreased the rate of crystallization and changed the final aluminous products from bayerite to nordstrandite and/or gibbsite and then to pseudoboehmite and/or amorphous material. In the presence of anions with a great affinity for Al, particularly at pH equal to or less than 9.0, the reaction products were commonly poorly crystalline or structurally distorted. In the range of pH 8.0 to 10.0 moderately or strongly chelating anions acted to retard or prevent olation and facilitated the formation of stable pseudoboehmite or X-ray-amorphous products. The stronger the chelating power or the higher the concentration of organic anions, the easier was the formation of pseudoboehmite or amorphous material.

Electron spin resonance (ESR) spectroscopy is used to investigate the nature of exchange sites on kaolinite. ESR spectra of exchangeable Cu2+ and Mn2+ on kaolinite indicate that divalent exchange ions are about 11–12Å apart on kaolinite surfaces and that planar Cu (H2O)42+ ions are oriented parallel to the surfaces. Solution-like spectra for exchangeable Cu2+ and Mn2+ are observed at high relative humidities, suggesting a high degree of mobility of exchange cations on kaolinite surfaces. The evidence seems to eliminate edge sites as being active in cation exchange at least in the acidic range of pH. Similar conclusions are derived from ESR studies of Cu2+-saturated talc and pyrophyllite. It is proposed that most exchange sites arise from ionic substitutions or mineral impurities in phyllosilicates.