Kyanite

Formula:Al2(SiO4)O

Name: Named in 1789 by Abraham Gottlieb Werner from the Greek word “kyanos”, meaning “blue,” the common color of the species. The French spelling, “Cyanite”, was commonly used by mineralogists through much of the 19th and early 20th centuries.

Color: Blue, white, light gray, green, rarely yellow, orange, pink

Lustre: Vitreous, Sub-Vitreous, Greasy, Pearly

Hardness: 5½ – 7

Density: 3.53 – 3.67

Crystal System: Triclinic

Member of: Nesosilicates

Polymorph of: Andalusite, Sillimanite. Common metamorphic silicate mineral. The generally bluish color is caused by Fe(II)-Fe(III) charge transfer.