| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1989: ¥100,000 (Direct Cost: ¥100,000)
Fiscal Year 1988: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1987: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
Many minerals which grew at a low temperature hydrothermal condition show sectors with abnormal optical properties between crossed polarizers. The origins of the sectors were studied by X-ray and optical methods. The formation mechanisms are explained as follows.
In low temperature aluminosilicates such as zeolites and adularia, various Al,Si orderings are produced by electron charge balance between alkali ions and Al,Si atoms on the crystal surface during growth. If Al,Si tetrahedron forms after ulkali ions on crystal surface, the tetrahedron will be preferentially occupied with Al ion. On the other hand, if the tetrahedron forms prior to the alkali ion, it will be preferentially occupied by Si. If growth steps are inclined to mirror plane, Al,Si structure will: be ordered with respect to the mirror, and the mirror will change into twin plane. If the steps are normal to the mirror, the structure will be disordered, and the mirror will be maintained during growth.
Also, the ordered arrangements of the Fe^<3+>, Al in garnet and the F,OH in topaz are produced on the side faces of the growth steps because of differences in ionic radii.
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