This unique stone is in the feldspar family. The main origin for this material comes from an island off of Labrador, but it has also been found in scandinavia.
Labradorite is interesting in that it appears to be just a gray rock, but when you look at it in the right angle of light, it flashes of blue, violet, and red can be dazzling. I bought a couple slabs at a gem & mineral show but have found it difficult to work. The stuff I got was full of fractures and difficult to get the color flash exclusive of the cracks.
For more information on Labradorite.