4mm Labradorite bullet bracelet from Madagascar.

The mineral labradorite is a calcium-sodium-aluminum tectosilicate with the chemical formula (Ca,Na)(Si,Al)4O8. It belongs to the feldspars. The colorless, white, gray or light green labradorite has a glass luster, a white stripe color, a perfect cleavage according to crystal plane [001] and a good according to [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 labradorisation, is caused by the refraction of light on microscopic crystals of various dark minerals that lie on the fission planes. Labradorite usually occurs shapeless or granular; the mineral rarely if ever forms crystals. Labradorite is undoubtedly the best known of the gemstones that display such a play of colours. When the stone is sharpened judiciously, the color play comes into its own even better. But the beautiful labradorisation can also often be seen on the raw chunks. There are few minerals that change color as strongly 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 in 1780 on the east coast of the Labrador Peninsula by a priest and named after the island by him. He found a large number of boulders with a striking gray color that changed color into dark blue and green nuances when turned. This discovery aroused great interest among scientists at the time and it was determined that this was a soda-lime feldspar or plagioclase. Labradorite is a common feldspar in metamorphic and igneous rocks like pegmatite. It is part of the plagioclase series (albite-anorthite). The labradorite type locality is on the Canadian Labrador Peninsula. Deposits can also be found in Australia, Madagascar, Mexico, Russia, the United States and Finland.