A member of the calcium- and sodium-containing plagioclase series of feldspars, the relative quantities of these two elements within labradorite ranges from roughly equal to around two-to-one in favor of calcium. As a gemstone, labradorite is noted for the multicolored, but primarily blue, adularescent effect that moves across its otherwise gray surface when then stone, viewer and/or light source is moved. In fact, this phenomenon is so distinctive that it is often referred to as “labradorescence”.
Labradorite was initially discovered in 1770 on Paul’s Island, which is located off the Canadian province from which it takes its name. However, the material has also since been found in Norway, Australia, Madagascar, Russia, Ukraine, United States (New York) and Finland, with the latter being the sole producer of an especially colorful variety known as “spectrolite”.
|