Absorption and photo-luminescence spectra of synthetic zircons doped with rare earth elements (REE) have been examined using a polarizing microscope spectrophotometer. Zircons containing each one of Tb²⁺, Tm³⁺, Ho³⁺ and Er³⁺ ions show characteristic absorption in the visible region, and the latter three ions in the zircon crystal give also peculiar photo-luminescence bands with enhanced intensities compared with their absorption bands. Although the zircons containing REE except the above four ions do not give any absorption bands in this region, Dy³⁺, Eu³⁺, Sm³⁺ and Pr³⁺ ions have emitted the characteristic photo-luminescence whose intensities are enhanced in the zircon crystal. Relative intensities of those luminescences decrease in the order of Dy, Tm, Eu, Sm, Er, Ho and Pr under UV-excitation. These luminescence bands are due to the well-known 4f–4f electron transitions within REE. Trivalent Sc in zircon crystal can also emit the luminescence, where the luminescent center may be formed in the forbidden band of the zircon. The other REE (Y, La, Ce, Nd, Gd, Yb and Lu) do not have any characteristic luminescent and absorption bands in the visible region.
The results are applied to assign the optical bands observed in natural zircons. Trivalent ions such as Dy, Tm, Eu and Sm are identified in the luminescence spectra under the microscope. While the other ions are not detected in both absorption and luminescence spectra of the zircon in this study.

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The annealing model proposed by Modgil and Virk (1985) for inorganic solids has been tested for some micaceous minerals being used as track detectors. Annealing experiments have been carried out in the temperature range of 200–700°C, on chlorite, biotite, muscovite and phlogopite, and it has been found from the results that the annealing rate Va is fitted well by the Modgil-Virk relation, Va=At⁻ⁿ exp(−Ea⁄kT). Here t and T are the annealing time and temperature; the activation energy, Ea, and the values of constants n and A for these minerals have been determined. The activation energy varies from 0.63 to 0.96 eV. It has been observed that the activation energy is independent of the annealing rate.

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The crystal structure of kalsilite at 950°C has been determined by high temperature single crystal methods. In the process of heating, the X-ray powder pattern of kalsilite changes at 865°C, which can be ascribed to the phase transition of this mineral. According to the drastic apparition of the extinction of hhl, 1-odd reflection at 865°C, the space group of kalsilite is assumed to change from P6₃ of the low form to P6₃ mc of the high form. In order to confirm this structural change, the single crystal structure analysis at 950°C was carried out with an automated four-circle diffractometer equipped with an electric furnace. As a result, it was confirmed that kalsilite undergoes a displacive phase transformation at the temperature mentioned above. The high form is hexagonal, P6₃mc, with a=5.30(1) and c=8.65(2)Å. Large thermal vibration of 0(1) atoms is observed along the direction perpendicular to the bonding of 0(1) and Si(Al) atoms. According to the bond distances between Si(Al)–0(1) atoms, the structure is considered to be partly changed into disordered kalsilite whose space group is P6₃/mmc. The translation equivalent subgroup relations are found among these three polymorphs, namely P6₃ (low-kalsilite), P6₃mc (high-kalsilite) and P6₃/mmc (disordered high-kalsilite). In the change of cell dimensions from room temperature to 950°C, there is also one more discontinuous point about at 650°C except that appeared at 865°C. A new phase transition may exist about at 650°C.

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Crystal structure and cation distribution of “cleavable olivines” with distinctive partings on (010), (100), and (001) from two ultrabasic rock masses (Oeyama and Happo-O’ne) were investigated by X-ray diffraction method. Crystal structure of the cleavable olivine does not possess any peculiarity in contrary to the Kuroda and Shimoda’s claim that it has some structural anomaly on the basis of strong 020 diffraction intensity observed by them. Strong 020 reflection in powder X-ray patterns is merely due to the preferred orientation. Cation distribution of Fe and Mg between M1 and M2 sites is random for Happo-O’ne olivine, and Fe atom slightly prefers for the M2 site for Oeyama olivine, indicating that both of the cleavable olivines are equilibrated at low temperature, which is consistent with petrologic evidences.

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Chemical compositions of micas from the Fujigatani, Kiwada, and Kuga tungsten mines, Yamaguchi Prefecture, Southwest Japan are obtained, and are compared with those from the vein-type tungsten deposits of the Kaneuchi, Ohtani, and Takatori mines.
Activity ratios of NaCl/KCl in hydrothermal solutions for the formation of the Fujigatani, Kiwada, and Kuga deposits are estimated from Na/K atomic ratios of muscovites. The ratios range from 5.5 to 2.9 at 400°C during the formation of muscovites. Na/K atomic ratios in muscovites from the Fujigatani, Kiwada, and Kuga mines are similar to those in muscovites from the Kaneuchi, Ohtani, and Takatori mines. Fluorine contents of muscovites from the studied tungsten mices are above 0.1 wt%, and those of biotites from the Kuga mine are above 3 wt%. These values are comparable to those in muscovites from the vein-type tungsten deposits of the Kaneuchi and Ohtani mines. Fluorine contents of micas from the three mices are higher than those from several porphyry copper deposits. High fluorine contents of micas are characteristic features of skarn-type tungsten deposits as well as vein-type tungsten deposits.

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