抄録
Tridymite was synthesized under various conditions with respect to starting materials and mineralizers in room pressures. Some of them, in its X-ray powder diffraction data, show the features of tridymite M and tridymite S, which were confirmed by Hill and Roy in sythetic tridymite under the hydrothermal condition, and the others are grouped into the intermediate between M and S. As the rusults of examination of their X-ray powder reflections and their D. T. A. curves, detailed criteria for grouping the tridymites by X-ray means in the present experiments were given along with the suggestions that these differences are due to the distortion of the structure at high-low inversion.
