A variety of andalusite called chiastolite may also be occasionally found at these sites. Polished cross sections of chiastolite are distinctive and attractive. Specific gravity is 3.1 to 3.2. Index of refraction is approximately 1.64. Pleochroism visible without a dichroscope sets andalusite apart from most gems.
Brazilian material appears green through the prism faces and deep brownish-red through the c axes.
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