Single crystals of clinopyroxenes with two different compositions in the system CaMgSi₂O₆–CaCoSi₂O₆ were synthesized under the condition where the crystals were coexiting with the melts. The compositions of the obtained crystals are [Ca_0.970Co_0.030][Mg_0.831Co_0.169]Si₂O₆ (abbreviated CaCoPx20) and [Ca_0.951Co_0.049][Mg_0.486Co_0.514]Si₂O₆ (abbreviated CaCoPx70). The crystals have the same structure as diopside (space group C2/c) with the cell dimensions a=0.97527(10), b=0.89261(8), c=0.52486(7) nm, β=105.856(9)°, Z=4, D_x=3.370(1) g·cm⁻³ in CaCoPx20, and a=0.97700(10), b=0.89395(8), c=0.52451(7)nm, β=105.720(9)°, Z=4, D_x=3.544(1) g·cm⁻³ in CaCoPx70.
The X-ray structure analyses gave unusually high residual electron densities up to about 6.9×10³ e·nm⁻³ for CaCoPx20 and 1.3×10⁴ e·nm⁻³ for CaCoPx70 at the position apart from the M(2) sites by about 0.04 nm along the b-axis in the difference Fourier maps based on the diopside model, where all of the Co²⁺ ions were located at the M(1) sites. These residual electron densities are due to partial replacement of Ca²⁺ by Co²⁺ at the M(2) sites, which amount to 3.0(4)% in CaCoPx20 and 4.9(4)% in CaCoPx70. The replacement was qualitatively confirmed by the ALCHEMI method under the condition of the (020) planar channeling.

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We measured Raman spectra of diamonds in ureilite meteorites and of diamonds synthesized under static high pressure, under shock-induced high pressure, and by chemical vapor deposition. The full width at half maximum (FWHM) and wavenumber position of a Raman line of F_2g (at 1332 cm⁻¹) are compared. Both the wavenumber and FWHM of the Raman line of ureilite diamonds are somewhat scattered around 1332 cm⁻¹ compared with those of diamonds produced under static high pressure. The latters show spectral features similar to the diamonds from the earth. The peak positions of some ureilite diamonds are shifted to smaller wavenumber than 1332 cm⁻¹, possibly due to lonsdaleite (hexagonal diamond). The peak position of the shock-produced diamonds is significantly shifted to smaller wavenumber, probably due to lonsdaleite and the FWHM is largely deviated. The FWHM of CVD diamonds is narrower than that of the shock-produced diamonds but larger than that of the diamonds synthesized under static high pressure. The peak position of some CVD diamonds tends to shift to higher wavenumber unlike shock-produced diamonds. The values of the FWHM of ureilite diamonds is closer to those of CVD diamonds than those of shock-produced diamonds.

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Distributions of trace ruthenium (Ru) in submilimeter sized areas of metallic FeNi minerals in iron meteorites have been studied by microbeam X-ray fluorescence analysis using synchrotron orbital radiation (SR-XRF) at Photon Factory, National Laboratory for High Energy Physics, Japan. Samples of iron meteorites of groups IA and IIA were irradiated by monochromatized X-ray beam of 22.5 and 23.0 KeV with beam size of 0.5×0.5 to 0.25×0.25 mm squares. A calibration curve was constructed for the standard FeNi alloys doped with 10 to 1000 ppm Ru. The Ru concentrations of ALH77283 (IA) kamacites were analyzed to be about 3 and 5 ppm. Ru in group IIA analyzed in this study (Bennett County, Coahuila, Scottsville, and Walker County) ranges from 13 to 33 ppm. These Ru concentrations of group IIA fall within the range of IIA previously reported. This study has shown that the non-destructive SR-XRF method can easily determine Ru concentration in iron meteorites, and that this method can be used to classify iron meteorites of groups IA and IIA on the basis of Ru versus Ni diagram.

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Calderitic garnet occurs in Al-poor granitic gneisses of the Donghai area in the ultra high-pressure terrane of eastern China. Calderitic garnet-bearing samples reequilibrated under greenschist-epidote amphibolite facies conditions, which postdated the ultra high-pressure metamorphism. Such samples contain quartz, K-feldspar and albite as major constituents with subordinate amounts of aegirine-augite, Zn-rich biotite (ZnO=2.7 wt% maximum), titanite, hematite, allanite and zircon with garnet. A small muscovite crystal occurs as an inclusion in albite. The calderitic garnet occurs as a rim around andradite-spessartine garnet or as anhedral grains in a matrix of equigranular felsic minerals. The empirical formula of the calderite-rich part is (Ca_1.69Mg_0.02Mn_1.16Fe²⁺_0.10)(Fe³⁺_1.58Al_0.40Ti_0.03)Si₃O₁₂. Calderitic garnet is stable in a Al-poor environment and probably cannot coexist with muscovite/paragonite and epidote as suggested by the idealized reactions of calderite+muscovite/paragonite → spessartine+K-feldspar/albite+quartz+H₂O and calderite+epidote → grossular-spessartine garnet+hematite+quartz+H₂O.

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Powder X-ray diffraction (XRD) patterns of phase B (Mg₁₂Si₄O₂₁H₂), anhydrous B (Mg₁₄Si₅O₂₄) and superhydrous B (Mg₁₀Si₃O₁₈H₄) were calculated using recently published structural data to facilitate phase identification by powder XRD technique. Comparison of these patterns with those of the previously reported hydrous phases revealed that superhydrous B and phase C are actually an identical phase. The XRD patterns were then used to identify the phases which appeared in the previous high-pressure experiments by the present author. A newly derived dehydration reaction of phase A (Mg₇Si₂O₁₄H₆) is as follows: 3 phase A = 2superhydrous B+Mg(OH)₂+4H₂O. The reaction was observed at 14 GPa and 1100°C. Superhydrous B coexisting with silica-rich phase was also detected in the 2Mg(OH)₂+SiO₂ system at ≥17 GPa. Therefore, superhydrous B might be stabilized in subducting slab at those depths.

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