The thermodynamic distribution coefficient of cadmium between calcite and solution has been determined from the measurement of the apparent distribution coefficient in the calcium bicarbonate solutions containing cadmium ions and bipyridine as a complexing agent with cadmium ions. The distribution of cadmium ions for aragonite in the solution containing magnesium ions (Mg²⁺: 1.2g/l) has also been examined. Thermodynamic distribution coefficient for cadmium was revealed not to be constant, although constant values were obtained for magnesium, copper, zinc, manganese, strontium, barium and other divalent ions.

View full abstract

The distribution coefficient of cadmium between calcite and solution has been measured in the calcium bicarbonate solution containing cadmium and chloride ions, which form complexes with cadmium ions. It has been confirmed experimentally that cadmium carbonate is present as a solid solution between calcitic calcium carbonate and cadmium carbonate in the carbonate precipitate formed in the solution system. The constant value of the thermodynamic distribution coefficient was not obtained in the solution system. It may have been caused by the very specific behavior of cadmium ions.

View full abstract

Mössbauer spectroscopy utilizing precise computer-based curve fitting procedures and X-ray diffraction methods have been used to study four deep-sea and one fossil marine manganese nodule. They have shown that X-ray amorphous goethite (α-FeOOH) and probably akaganéite (β-FeOOH) are the secondary iron oxidehydroxide phases present in the deep-sea nodules. The fossil nodule contained goethite with a larger particle size (approx. 350Å) which had presumably been formed by the recrystallization of X-ray amorphous goethite and/or the alteration of the metastable akaganéite.

View full abstract

The basalts of Norfolk Island range from tholeiites through transitional basalts to alkali olivine basalts, and plot in a unique field on a Ti-Zr-Y diagram. REE abundances in seven representative samples are similar to those in tholeiites and alkali olivine basalts from Hawaii, i.e. light REE enrichment relative to chondrites, and a slightly higher ^La/Yb value for the alkali olivine basalts relative to the tholeiites. Three tholeiitic samples with anomalously high Y (84-105ppm) show unique REE patterns for basaltic rocks, with a relative enrichment of the middle REE. Apart from Y and REE these samples are chemically identical to the ‘normal’ Y-REE tholeiites from Norfolk Island, and it is suggested that the unique Y and REE contents are due to variable Y and REE concentrations in an accessory mantle phase such as apatite and/or the Y acceptor RE phosphate minerals such as xenotime or samarskite inhomogeneously distributed in the source region for the basalts.

View full abstract

A detailed discussion is made on the calculation of the thermodynamic parameters through the element partition reaction by the method of least squares curve fitting. Systematic calculation of adjusted parameters is also given on the statistically sound basis. The thermodynamic properties of olivine, orthopyroxene and clinopyroxene are calculated by the proposed least squares method for the existing data. Results of the previous and new treatments on the orthopyroxene-clinopyroxene pair are compared in Fig. 1 as an example.

View full abstract

The behavior of borate-boron in a calcium bicarbonate parent solution during the precipitation of calcium carbonate has been studied experimentally. The amount of borate-boron coprecipitated with calcium carbonate is proportional to the concentration of borate-boron dissolved in a parent solution, and this relationship is affected by the crystal form of calcium carbonate precipitated and the concentration of sodium chloride dissolved in the parent solution. Borate-boron is easily coprecipitated with aragonite rather than with calcite. These experimental results agree with the trend of boron content in carbonate skeletons of marine organisms such as bivalved mollusks. There is a difference in the influence of sodium chloride dissolved in a parent solution on the coprecipitation between calcite and aragonite: The amount of borate-boron coprecipitated with calcite increases with increasing concentration of sodium chloride in a parent solution, whereas the amount of borate-boron coprecipitated with aragonite decreases with increasing concentration of sodium chloride in the parent solution. This fact suggests that the mechanism of the coprecipitation of borate-boron with calcite is different from that with aragonite. Borate-boron dissolved in a parent solution has little influence on the crystal form of precipitated calcium carbonate.

View full abstract

A new aluminium silicate has been produced under hydrous conditions from Al₂O₃-SiO₂ oxide mixes with Si/Al ratios close to unity, at pressures greater than 100 kilobars and at about 1, 000°C. X-ray powder photographs indicated one dominant new phase. From analyses of the electron diffraction Laue zones of minute fragments (∼1μm), a monoclinic structure that fitted the X-ray powder results was identified. This monoclinic structure is described in terms of nine close-packed layers of oxygen with the unit cell containing 72 oxygen atoms. Assuming Si/Al equals 1, the composition of this phase is Al₂₀Si₂₀O₇₂H₄. The calculated density of 4.03 g/cc is in good agreement with the value of 4.02 g/cc estimated from the refractive index measurements.

View full abstract

In this work the conditions required for the presence of two solid phases in equilibrium with a solution are discussed with special reference to the co-existence of magnesium calcites and dolomite in seawater. The criterion is determined in terms of the phase rule and of the solid-seawater ratio.

View full abstract