Description
The mineral labradorite is a calcium-sodium-aluminum tectosilicate with the chemical formula (Ca,Na)(Si,Al)₄O₈. It belongs to the feldspars. Colorless, white, gray, or light green labradorite has a vitreous luster, a white streak color, perfect cleavage along the crystal plane [001], and good cleavage along [010]. The average density is 2.69 and the hardness is 7. The crystal system is triclinic, and the mineral is neither radioactive nor magnetic. The characteristic play of colors, called labradorization, arises because light refracts on microscopic crystals of various dark minerals lying on the cleavage planes. Labradorite usually occurs amorphous or granular; the mineral almost never forms crystals. Labradorite is undoubtedly the best-known of the gemstones that exhibit such a play of colors. When the stone is cut judiciously, the play of colors is displayed even better. However, the beautiful labradorization is often visible on the rough chunks as well. There are few minerals that change color as dramatically as labradorite. The name of the mineral labradorite is derived from the Labrador Peninsula in Canada, where it was first described. The stone was discovered on the east coast of the Labrador Peninsula in 1780 by a priest, who named it after the island. He found a large number of erratics with a striking gray color that changed to dark blue and green nuances when rotated. This discovery aroused great interest among scientists at the time, and it was determined that this was a sodium-calcium feldspar or plagioclase. Labradorite is a common feldspar in metamorphic and igneous rocks such as pegmatite. It is part of the plagioclase series (albite-anorthite). The type locality of labradorite is located on the Canadian Labrador Peninsula. Deposits are also found in Australia, Madagascar, Mexico, Russia, the United States, and Finland.
