Labradorite
Labradorite, a rock that consists of aluminum, calcium, and sodium silicates. It is a variety of feldspar, found in dark gray crystalline masses that are easily split into slabs. Some varieties of labradorite are beautiful when polished, showing rich shades of blue, green, and bronze. Labradorite is used for table tops and for small ornamental objects. It is found in parts of Europe and the United States, but the finest grade occurs in Labrador.