Labradorite, ((Ca,Na)(Al,Si)4O8 is a feldspar mineral and is an intermediate to calcic member of the plagioclase feldspar series. When polished it's iridescent properties are revealed in an effect known as labradorescence. For this reason, it is often used to make jewelery. This specimen displays the plagioclase content, which is usually 40" to 60%. and comes from Larvic in Norway.