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Abstract. The diamagnetic properties of sheetsilicates are studied by measuring the magnetic orientation of micron-sized crystals. In the case of synthetic phlogopite with the average diameter of 0.65 gm and the thickness of 0.2 gm, the alignment of the grains is achieved in the magnetic field below 35 kOe. The planes of the platy single-crystal grains were alignned parallel to the field when the alignment was achieved. The alignment of the grains is realized because the field-induced anisotropic energy, caused by the diamagnetic anisotropy in the mineral's crystal structure, exceeds thermal agitation energy in the applied field. By analyzing the field dependence of grain alignment, the diamagnetic anisotropy per formula unit, A Z, of sheetsilicate mineral is estimated even if a large single crystal is not provided. The field-induced anisotropic energy is proportional to NA)~ where N is the number of molecules in the grain.A linear correlation has been found between the A X value and the F/OH mole ratio among the measured sheetsilicates. This correlation supports the assumption that the hexagonally packed oxygen-layer in the crystal lattice induces the anisotropies of the sheetsilicates.

Translations induced by a field gradient force are newly reported on various diamagnetic crystals that are released in microgravity (mG) produced by a drop capsule. A crystal released near a field center (B $ 1 T) with negligible initial velocity translates through a diffused gas medium, in a direction of monotonically decreasing field. In a given field distribution, the velocity of the crystal uniquely depends on the intrinsic diamagnetic susceptibility DIA of the material; velocity is independent of the mass m of particles. The general features of rotational oscillation caused by field-induced anisotropy energy are studied on the basis of previous experimental data; the rotational oscillation of a magnetically stable axis with respect to the direction of homogeneous field has recently been observed for various diamagnetic crystals in mG. At a given field intensity, the period of oscillation is uniquely determined by the intrinsic diamagnetic anisotropy Á DIA and Im À1 of crystals; I denotes the moment of inertia of crystals. The period is independent of m. In a long duration of mG, field-induced translation and rotation are generally observable for diamagnetic solids at low field intensities. By observing the two motions in mG, DIA and Á DIA are obtained without introducing a sample holder, and without performing m measurement; magnetization becomes detectable for a single particle with a limitlessly small size, under the condition that field-induced motions of particles are observed.