Kyanite’s name derives from the Greek kyanos, meaning “dark blue.” It occurs in metamorphic rocks such as schist and gneiss associated with garnet, staurolite and micas; and in eclogites. The presence of kyanite in rocks indicates that they have undergone moderate temperatures and medium to high pressures during metamorphism. Associated minerals include andalusite, corundum, and staurolite.
Kyanite has a vitreous luster, often with irregular streaks. It is difficult to cut because of its variable hardness and cleavage. This variable in hardness is also known as disthene; meaning “double strength,” after the hardness, which is greater across the crystal than lengthwise.
The colors of gem-quality kyanite are shades of blue, white, green, gray and occasionally black. It is transparent to translucent and the luster ranges from vitreous to pearly. In jewelry a great deal of bead and cabochon material contains inclusions of quartz, pyrite crystals, hematite flakes and fibers of ilmenite and rutile. It makes a rather brittle gemstone that is susceptible to splitting. It requires careful handling, so any polishing should be done at low speed and ultrasonic and chemical cleaners should not be used. However, it is not sensitive to heat.
Kianite can be found in Bahia, Brazil; the St. Gotthard region of Switzerland; Urals in Russia; and Yancy County, North Carolina
Kyanite can be confused with aquamarine, benitoite, iolite, dumortierite, and tourmaline; and very often with sapphire.