The andalusite here described was newly found in a pegmatite at Kabutsu, 5km north of Miharu Town, Fukushima Prefecture. Essential minerals of the pegmatite are quartz and microcline-perthite. Andalusite as an accessory mineral was found in the perthite together with muscovite. The andalusite of rose red color is abundant as radial masses. 5 to 20cm in length and includes several small crystals of fergusonite and corundum.
The specific gravity determined by a pycnometer was G^21°_4°=3.150. Color is red in thin-section and its pleochroism is strong. X=rose red, Y= Z=colorless. The refractive indices are: α=1.632, β=1.638, γ=1.642, γ-α=0.010. The optic axial angle measured by a universal stage is (-) 2V=83°. The result of chemical analysis by S. Hasegawa of our Institute, is given in Table I. The folmura of the andalusite calculated by Tom. Barth's method is expressed as (Al_63•1 Fe³+_30.7) Si_33•2 O₁₆₀. As shown in Table II, the rose red color of the andalusite increases in intensity with an increase of Fe³+ ion. The relations between the crystal structure and the optical properties (Table III) of the andalusite, sillimanite and cyanite are described.

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