Rhodonite and pyroxmangite have been found to coexist in nature. These minerals were investigated by the single-crystal X-ray method and with an electron probe microanalyser. The two phases intergrown hold a certain orientational relation with each other, and the chemical compositions of the two phases are different from each other, the parts rich and poor in Ca corresponding to rhodonite and pyroxmangite respectively. This orientational relation was found to agree with that caused by an artificial thermal transformation of pyroxmangite into rhodonite, and to be in conformity with the principle of densest-zone preservation. The mechanism of intergrowth of the two phases in nature was explained with a reasonable process of cation and silicon migration in pyroxmangite to form rhodonite.

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Microheterogeneity of glass and its behavior after heat treatment have been investigated by small angle X-ray scattering (SAXS) on the glasses of Li₂O–SiO₂ system.
For Li₂O·4SiO₂ glass, the SAXS curve exhibits a little hump. It disappears on prolonged heating. For Li₂O·3SiO₂ glass and Li₂O·2SiO₂ glass, the SAXS curves decline monotonously with the increasing scattering angle. It is concluded that the glasses studied, irrespective of their compositions, have microheterogeneities of about 20Å in spherical diameter, and that these values increase with the increasing time of heating.

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X-ray diffraction patterns have been obtained from Li₂O·xSiO₂ glasses (x=2, 3, 4). By the Fourier analysis the radial distribution function was evaluated, from which interatomic distance and coordination number were obtained. Their values were compared with those of silica glass and of Li₂O·2SiO₂ crystal. In Li₂O·2SiO₂ glass (one phase), the distance of Si–O, O–O and Si–Si was 1.62, 2.65 and 3. 07Å, respectively. That is, the structure of short range order of Li₂O·2SiO₂ glass was almost similar to that of Li₂O·2SiO₂ crystal. In Li₂O·4SiO₂ glass, which undergoes phase separation and is composed of SiO₂-rich phase and Li₂O·2SiO₂-rich phase, the fifth peaks in the radial distribution curve were found at about 4.8Å and 5.1Å. And the radial distribution curve of Li₂O·3SiO₂, which undergoes slight phase separation, indicated the intermediate value between Li₂O·2SiO₂ glass and Li₂O·4SiO₂ glass.

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The crystal of synthetic rhodonite, Mn_0.685Mg_0.315SiO₃, has cell dimensions, a=7.545(2) Å, b=11.782(3) Å, c=6.663(2) Å, α=92.69(2)°, β=94.32(3)°, γ=105.71(2)°, and space group P-1; Z=10, D_x=3.55g·cm⁻³. An isotropic refinement of the structure to R=4.0% has revealed the ordering scheme of Mg in the rhodonite type structure; with the use of Takéuchi’s site notation for cations (Takéuchi, 1977), the site occupancies of Mg are expressed as follows: 0.304(6) and 0.254(6) respectively at M10 and M11, and 0.132, 0.519(6) and 0.366(6) respectively at M21, M22 and M23. The geometrical characteristics of the octahedron about M22 can account for the preferential concentration of Mg in the site. The mode of structural variation of pyroxenoids according to the change in chemistry has been discussed in terms of the mean M–O distances of M1i cations (i=0, 1 for rhodonite) and the lengths of l_j and l₀, the former being the distance between apical oxygen atoms, associated M1i of a jth pair of adjacent tetrahedra in the same silicate chain, and the latter the distance between similar oxygen atoms of a specific pair of tetrahedra which are linked to the offset tetrahedron between them; l₀ which is in fact an edge of M10 octahedron, significantly varies with the change in chemical composition. An analysis on the mode of structural variation has led to a view that pyroxenoids having silicate chains longer than those of ferrosilite III would not exist.

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