http://fazaldindiamonds.darkbb.com/tanzanite-f4/-t1.htm Tue, 22 Jan 2008 17:58:42 GMT 10 http://i80.servimg.com/u/f80/11/90/59/95/i_logo10.jpg http://fazaldindiamonds.darkbb.com/tanzanite-f4/-t1.htm http://fazaldindiamonds.darkbb.com/tanzanite-f4/properties-of-tanzanite-t4.htm Admin Properties of Tanzanite Tanzanite (a variety of zoisite) Composition Ca2Al2(SiO4)3(OH) Hardness (Mohs) 6 to 7 Specific Gravity 3.35 (+ 0.10, -0.25) Refractive Index 1.691–1.700 (0.008–0.013); Doubly refractive, biaxial positive Crystal System Orthorhombic Colors Blue, violet, green, brown Pleochroism Strongly trichroic Dispersion 0.021 Cleavage Perfect in one direction Phenomena Cat’s eyes are known. Many tanzanites display a color shift from blue in daylight to violet ... Tanzanite Tue, 22 Jan 2008 17:58:42 GMT http://fazaldindiamonds.darkbb.com/tanzanite-f4/properties-of-tanzanite-t4.htm#8 http://fazaldindiamonds.darkbb.com/tanzanite-f4/properties-of-tanzanite-t4.htm