Mineral Species: Kyanite

Chemical Formula: Al2SiO5

Chemical Name: Aluminium Silicate

Mineral Class: Nesosilicate

Mineral Notes: Kyanite is a polymorph with two other minerals; Andalusite and Sillimanite. This means it has the same chemical composition but different crystal structure to these minerals. It is a particularly variable species froming blue, green and occassionally black columnar crystals. Kyanite also has a unique property of having a variation in hardness in the same crystal. The hardness is approximately 4.5 when scratched parallel to the long axis of the crystal and approximately 6.5 when scratched perpendicular to the long axis.

Description: Numerous elongated crystals of blue Kyanite embedded in white Quartz. The Kyanite is partially transparent and has a bright glassy luster. It is therefore quite gemmy. Some of the crystals are twinned.

Location: Itabirito, Minas Gerais, Brazil.