Coexisting jadeite and omphacite were found in a jadetite from the Ohmi area and in a jadeite vein from the Shibukawa area, central Japan. EPMA scanning traverses confirm the existence of miscibility gaps between jadeite and omphacite. The gaps are impure jadeite (Jd>86)–omphacite (Jd<65) in the Ohmi sample and jadeite (Jd>90)–impure jadeite (85>Jd>77) and impure jadeite (85>Jd>77)–omphacite (Jd<50) in the Shibukawa sample. It is concluded that the miscibility gap narrows with increasing grade, especially from the omphacite side, and two miscibility gaps, which were found in the Shibukawa sample, occur only under low-grade metamorphic conditions.

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Twenty-six natural lead-bearing barite specimens (hokutolite) from Peito Hot Spring, Tamagawa Hot Spring and Kawarage Hot Spring were studied to refine the relationship between their lattice constants and their chemical compositions.
It was found that the lattice constants of natural lead-bearing barite show negative deviations from the Vegard’s rule, which are probably due to small amounts of the third component of strontium. The negative deviations of the unit cell volume are ranging from 0.2 ų to 2.4 ų from the Vegard’s rule in terms of mole ratio of lead to barium. These deviations are correlated with the strontium content (as SrO) ranging from 0.07 wt.% to 1.79 wt.%.There is also a weak correlation between these deviations and calcium contents.

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Kalsilite shows the domain structure corresponding to the disordered oxygen atoms at two mirror equivalent sites. The domain structure was considered to be due to the high-low inversion, and the structural model of the high-form was constructed. The heating experiment was carried out, which revealed that the X-ray powder pattern changes at 1138 K. It was confirmed that kalsilite undergoes a displacive transformation like quartz and tridymite. The high-form is hexagonal, probably P6₃mc, with a=5.30(1), c=8.65(1)Å. The high-form was also considered to be divided into two groups, high-kalsilite (P6₃mc) and disordered high-kalsilite (P6₃⁄mmc). The Zellengleichen subgroup relations are found among these three polymorphs.

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Ruby, purplish red to pink, found in the Hodono valley, Ehime Prefecture, occurs in an amphibole-zoisite rock with a minor amounts of garnet, paragonite, and chlorite.
The corundum is idiomorphic granular, up to 5 cm in diameter, and transparent purplish red to colorless. Optical properties are uniaxial (−) ε=1.761(2), and ω=1.769(2). Density (meas.) is 3.887(5). Red fluorescence is displayed by long (3650 Å) and short (2536 Å) wave ultraviolet rays. Cell dimensions are a=4.760(1), c=12.992(3)Å, c⁄a=2.729, and cell volume 254.9(1)ų. Infrared absorption bands occur at 780 cm⁻¹, 641 cm⁻¹, 595 cm⁻¹, 450 cm⁻¹, and 378 cm⁻¹.
Microprobe analyses for the minor oxide abundance of corundums with dark purplish red to light purplish pink color are Fe₂O₃ 0.44−0.39 vrt%, Cr₂O₃ 0.44−0.01 wt%, SiO₂ 0.0−30.00 wt%, and MnO 0.01−0.00 wt%. The abundance of Cr₂O₃ varies among different grains or within a single grain, and corresponds to the shade of red.
The mineral assemblage of the corundum is briefly discussed.

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A manganoan hedenbergite Hd₆₈Jo₃₂ from the Nakatatsu mine, Fukui Prefecture, Japan, is described. The mineral occurs in the hedenbergite skarn zone. Lattice constants are: a=9.868(6)Å, b=9.047(5)Å, c=5.255(3)Å and β=104.84(6)°. The space group is C2⁄c and Z=4. The crystal structure of the mineral was refined to an R factor of 3.8% for 505 observed reflections. The structure is very similar to that of hedenbergite.

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