Barium-containing alkali feldspars from the Taguchi mine, Aichi Prefecture, Japan were examined by an electron-probe microanalyser, the X-ray Weissenbeig camera and so on. Barium-containing alkali feldspars (Bf feldspars) are constructed of the patches of albite, the needles of hyalophane and the host of barium orthoclase. It is considered, as pointed out by Gay and Roy (1968), that barium orthoclase-hyalophane assemblage was formed by exsolution. On the other hand, the patches of albite are considered to have been formed by “replacement” after the above exsolution.

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Fukalite occurs in spurrite-gehlenite skarns at Fuka, and Mihara, Okayama Prefecture, and at Kushiro, Hiroshima Prefecture. It is an alteration product of spurrite and is associated with calcite and/or xonotlite. It is found as pale brown to white crystals up to 0.2 mm long.
The crystals are orthorhombic a 5.48(1), b 3.78(1), c 23.42(3)Å, Z=2. They are optically biaxial, 2V about 90°, refractive indices α 1.595, β 1.605, γ 1.626 for the Fuka materials, elongation negative. The wet chemical analyses give an ideal formula Ca₄Si₂O₆(OH)₂(CO₃). The density is 2.770 g/cm³ (observed) and 2.77 g/cm³ (calculated). The strong lines of the X-ray powder pattern are 2.854, 3.084, 2.926, 2.388, 1.756 and 5.86 Å.
The mineral is named after the first locality, Fuka, Okayama Prefecture, Japan.

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Tridymite from the Steinbach meteorite is monoclinic with cell dimensions: a 18.54, b 5.00, c 23.83 Å, β 105.70° and space group C2⁄c or Cc. Its diffraction pattern shows an extremely large number of structural absences, leading to pseudo-orthorhombic superlattice with cell dimensions A 51.86, B 30.00, C 49.20 Å. The method of twin analysis (Ito and Sadanaga, 1970) was applied uniquely to derive a crystal lattice from the twin pattern. Pseudohexagonal twinning about the [-201] row of the true monoclinic lattice satisfactorily accounts for these unusual structural extinctions. The symmetry of the twin is represented by the six-color symmetry symbolism. A possible mechanism of twin formation is proposed, based on the recently determined low tridymite structure.

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Vacuum deposition method is applied for preparation of low temperature phases of iron-sulfides. Deposited films were examined by means of electron diffraction and identified to be mackinawite with small amounts of α-iron and greigite. The main reflection of mackinawite, 001, appeared as strong arcs by tilting the film because of the preferred orientation of (001) of mackinawite parallel to the substrate. Since mackinawite is synthesized anhydrously by this method, mackinawite is one of the phases belonging to the Fe–S system.

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