The crystal structure of katayamalite
1985 年 12 巻 5 号 p. 206-217
詳細
1985 年 12 巻 5 号 p. 206-217
The crystal structure of katayamalite has been determined by Patterson method and refined by the least-squares method using single crystal diffractometer data, giving R = 0.057 for 5785 reflections. Formula: (K,Na)Li3Ca7(Ti,Fe3+,Mn)2[Si6O18]2(OH,F)2. Cell dimensions: a 9.721(2), b 16.923(3), c 19.942(3)Å, α 91.43(10)°, β 104.15(11)°, γ 89.94(10)°, space group C-1, Z = 4; or a 9.763(2), b 9.721(2), c 19.942(3)Å, α 104.15(11)°, β 81.76(9)°, γ 119.92(10)°, space group P-1, Z = 2. Katayamalite is a ring silicate with two-layered structure parallel to (001), and consists of Si6O18 rings connected with Ca–(O,OH) octahedral sheets, and with Ti–O octahedra, Li–O tetrahedra, and 12-fold K polyhedra. The crystal structure of katayamalite is very similar to that of baratovite. However, the distortion in the katayamalite structure results in the lower symmetry of triclinic system. Half of the motifs of the katayamalite structure and the baratovite structure are similar to that of cordierite, and we can propose the following structure series; beryl → cordierite → katayamalite and baratovite.
