Crystals of ferrian braunite were synthesized using evacuated silica glass tube at 1000°C, and the chemical composition and the cell dimensions of the run products were determined. Under this condition, ferric ions replaced trivalent manganese ions of braunite up to 40%. The cell dimension, especially the length of the c-axis, increases in proportion to Fe³⁺⁄(Fe³⁺+Mn³⁺) of braunite, in spite of the nearly equal radius of ferric ion to that of trivalent manganese ion. This substitution is thought to bring about the releasing of distortion of trivalent manganese ions by Jahn-Teller effect and to result in the increase of cell dimension.

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Fe–deficient nonstoichiometric olivine related minerals,    _x⁄2Fe_x³⁺Fe_2−(3⁄2)x²⁺SiO₄ have been identified in samples from many localities in Colorado, U.S.A. and in Japan, where     denotes vacancies in the structure. It is possible to classify these Fe–deficient olivine minerals into several crystallographically-distinct species. Laihunite has monoclinic symmetry and this include two superstructures, the laihunite–2M and laihunite–3M types in Ramsdell notation. Laihunite associated with the laihunite–3M superstructure is most commonly found in rock types such as metamorphic rock, migmatite, pegmatite and is, in many cases, accompanied by magnetite. Laihunite associated with the laihunite–2M superstructure was found in dacite and is accompanied by hematite. Fe–deficient manganoan olivine occurs in pegmatites, has orthorhombic symmetry, and is termed as ferri-knebelite in this study in order to distinguish it from other related materials. Based on these results, it can be said that the Fe–deficient olivine minerals are fairly common in many rock types and are widespread in their occurrence.

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Kamiokite occurs as granular to thick tabular crystals with hexagonal outlines, up to 3 mm in diameter, in molybdenite-quartz veinlets in the Kamioka Ag–Pb–Zn mining area, Gifu Prefecture, central Japan. Chemical formula: (Fe_2.01Mn_0.03)_2.04Mo_2.98O₈ on the basis of O = 8, or ideally Fe₂Mo₃O₈. The mineral is hexagonal with space group P6₃mc, a=5.782(2), c=10.053(3) Å, Z = 2, cell volume = 291.09 ų; calculated density = 6.02 gm/cm³. Strongest X-ray powder diffraction lines and their relative intensities (subject to preferred orientation): 5.03(100), 3.55(90), 2.509(75), 2.430(55), 2.006(40). Kamiokite is opaque, iron black in color, and metallic to submetallic in luster, with black streak. Cleavage [0001] perfect, fracture even. Vickers hardness (50 g load) is about 600 kg/mm², Mohs hardness 4.5. Density measured 5.96 gm/cm³. In reflected light the mineral is gray with olive tint. Strong reflection dichroism, gray to olive gray. Anisotropism is strong, from light brownish gray to dark greenish gray. Reflectances (R_max, R_min) in air: 23.6, 16.0% (480 nm); 22.9, 15.3% (546 nm); 22.2, 14.7% (589 nm); 22.1, 14.3% (657 nm). The name is for the locality.

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