Labradorite is a mineral: it is a a plagioclase feldspar, a mixture of silica and aluminum. Nuumite, Moonstone, Sunstone and Amazonite are also feldspar minerals, and they have very similar compositions. Some very colorful labradorite stones formed in Finland are known as Spectrolite. The silver-grey labradorites from Scandinavia are called Larvikite. Labradorite is named after its location of discovery on the Isle of Paul, Labrador, Canada. It was also found in Australia, Madagascar, Mexico, Russia and United States.
Feldspar formation can take place in several ways, including crystallization of magma, compression under high temperatures and high pressure deep inside the Earth, or particles broken and fused together in sedimentary stone.
A particular aspect of labradorite is its Schiller effect (called labradorescence). An iridescent optical interference of light caused by diffraction from microscopic particles. The light is not reflected at the surface: it enters the stone and hits areas of a specific lamellar separation. Not every labradorite stone has lamellar separation: it is only seen in minerals that had a very, very slow cooling process that allowed ions to separate.
The stone of the Northern Lights:
Aurora Borealis, one of the most beautiful natural displays of light on Earth, was said to be trapped inside Labradorites, waiting to be found by the Inuit and Beothuk people. One warrior tried to free the light with his spear, but he failed to free it all, so the magnificent spectrum of light was crystallized inside Labradorites forever.