Labradorite

Labradorite is a calcium-rich feldspar of the plagioclase series, first identified in Labrador, Canada, and holding between 50 and 70 per cent anorthite; Wikipedia's infobox lists it as a variety of anorthite. It is a common grain in basalt, gabbro and other dark igneous rocks, and the rocks called anorthosites are made almost wholly of it. Its type area is Paul's Island near Nain, and it is also reported from Norway, Finland, Madagascar, China, Australia and the United States, among other places. Many pieces show labradorescence, a flash of colour that appears and vanishes as the stone is turned; stones from Canada or Madagascar mostly flash blue, grey and green. The effect comes from extremely thin layers that separate inside the crystal only when the rock cools very slowly, so not every piece has it. Spectrolite, an unusually colourful kind found in 1940 in the south-east of Finland, at Ylämaa, is now a brand name for Finnish material. Hall, who gives spectrolite as another name for the stone, calls labradorite a deeply mystical and protective stone that keeps unwanted energies out of the aura, grounds spiritual energy, and stirs intuition and psychic gifts. She also says it banishes fears, brings buried memories to the surface, and lends strength and perseverance through times of change, naming it a stone of transformation.