Cation distribution in seven monoclinic amphiboles of tirodite-dannemo-rite series has been determined by infrared OH streching bands and ⁵⁷Fe Mössbauer spectra. The results indicate that Mg is concentrated in M2 site rather than in (M1, M3) sites but very few in M4 site, and that Fe²⁺ is contained more in (M1, M2, M3) sites than in M4 site. This tendency of Fe²⁺ dis ribution in the tirodite-dannemorite series is considerably different from that in Mg-Fe amphiboles, which is caused by the fact that Mn prefers M4 site rather than (M1, M2, M3) sites. Manganese ion was found to be distributed not only in M4 site but also in (M1, M2, M3) sites except in one sample, in which Mn content was low. The proportion of Mn in M4 site decreases with the increase of total Fe²⁺, which suggests that there is an intra-crystalline equilibrium of Mn and Fe²⁺ between (M1, M2, M3) sites and M4 site. The quadrupole splitting of Fe²⁺ in M4 site becomes smaller with increase of total Fe²⁺, and this tendency indicates that the distortion of M4 octahedron also increases with the increase of Fe²⁺.

抄録全体を表示

Some minerals of the Au-Ag-Te system, krennerite, petzite and hessite, have been reported from the Daté mine, southwestern Hokkaido by Watanabe and Yamaguchi (1942a, b) and Ishibashi (1960). We have re-examined the (Au, Ag) Te₂ type minerals from the mine by the X-ray powder diffraction and EPMA methods. As the results, calaverite was newly recognized but krennerite, reported bythem, was not found in this sample. And, cassiterite and pyrite associated with calaverite were confirmed by the X-ray powder diffraction, EPMA methods and optical observations. This mineral paragenesis is very rare (e. g., Kelly and Goddart, 1969). Based on the experimental results (Nakata et al., 1980) and the mode of occurrence (Watanabe and Yamaguchi, 1942a, b), on the other hand, calaverite is considered to have been formed under alkaline conditions with the variations of the formation temperature.

抄録全体を表示

A Weissenberg camera screen with two slits for x-ray single crystal study was developed to record two layers of reciprocal lattice simultaneously. We opened the zero-layer in the lower half of the film and first-layer in the upper half by using crystals of aragonite and diamond. The computer program was made to analyze the reflections from the twinned diamond, and it is confirmed that this diamond is combined by spinel law. This attachment will be very useful for rappid determination of lattice constants and space groups of crystals, especially under unstable condition and radiation damage.

抄録全体を表示