Also known as disthene
, kyanite is a gemstone
discovered in the 19th century
. It is usually found in mountain regions (often in the same places as andalusite
); deposits have been found in North Carolina
. The most valuable stones are blue or blue-green, but it also is found in gray, yellow, white, and clear.
As a mineral, kyanite is interesting because its rating on the Mohs hardness scale changes from 5.00 to 7.00 depending on the direction of its cleavage (which way you are trying to cut it). This makes it somewhat difficult to cut and facet for jewelry though. The color is beautiful enough that synthetic corundum, spinel, and quartz have been used to imitate it.