Labradorite
Labradorite is a Plagioclase Feldspar found in magmatic igneous and metamorphic rock. Discovered in 1770 on St. Paul Island, Labrador, Canada, Labradorite was named for this site - a locale famous for producing the variety of stone containing the iridescent schiller effect - in this instance called "labradorescence".
This gemstone is also found in Australia, Finland, India, Madagascar, Mexico, Newfoundland, Norway, Russia and the United States