Congratulations! You have found a Kyanite gemstone! Kyanite's name comes from the Greek word kuanos meaning "deep blue".
Kyanite is a 4-4.5 hardness on the Mohs scale, and it great ot use in earrings and pendants.
Kyanite is typically blue, but can also be gray, colorless, yellow, white, or green, with a sapphire-like blue being the most desired color.
In ancient times, kyanite was believed to work as a compass needle when suspended from human hair. Travelers took kyanite with them as they entered unknown lands.