http://www.zzhw66.com/ andalusite are orthorhombic crystal extends along the C axis was inclined side column. Because of the angle between the cylinders is about 89 ℃, so look very much like the four cylinder. Radial aggregates, granular, visible interspersed twinning. Solutions cylinder (110) completely. Color is gray, yellow, red, purple, green and brown. Hardness of 6.9 to 7.4. The proportion of 3.12 ~ 3.19. Thin colorless, sometimes slightly pink hue, the color is often not evenly distributed in the same one-sided, shades, in spots. Parallel or symmetrical extinction, with weak pleochroism: Npi pink (1.629 ~ 1.639), Nm light green (1.633 ~ 1.639), Ng light green (1.637 ~ 1.650). From moderately positive real; (-) 2V = 80 ~ 86 °. Nearly a square cross-section, and sometimes that nearly two orthogonal cleavage. In andalusite, and sometimes see a black carbonaceous material inclusions (may be called empty spar). The use of multi-colored features andalusite it can be and sillimanite distinction.