Note the diamond-shaped inclusion cloud to the top right, which is the center of the crystal, and the four inclusion trails that radiate from the corners of the diamond. Note the small garnet just to the right of the diamond. Two cleavages intersecting at approximately right angles are visible. Note the isotropic garnet, and the matrix at the right edge of the andalusite crystal. The kyanite crystals are colorless, have high relief, and have a strong cleavage parallel to their length.
Relief is much higher than muscovite, which surrounds the kyanite.
40x Gassetts Schist Kyanite in a muscovite-biotite schist. The kyanite crystals are have interference colors up to upper 1 st order, much lower than the surrounding muscovite. Most sections yield slightly inclined extinction, as expected from its triclinic symmetry. Sillimanite is colorless, has relief much higher than muscovite, has diamond-shaped end sections, and has only one cleavage. Sillimanite has birefringence up to 2 nd order blue, somewhat higher than kyanite and much higher than andalusite.