Labradorite

Labradorite is no longer regarded as an independent mineral, but as a mineral mixture of albite and anorthite from the group of feldspars and the mineral class of silicates. Labradorite is characterized by its play of colors on its cleavage surfaces, which is referred to as labradorescence. The range of colors is from blue and violet to green, yellow and orange. Some rare specimens show all colors at once. The colors shown come from the laminar intergrowths in the crystal. These intergrowths are due to compatible chemistry at high temperatures, which becomes incompatible at low temperatures, causing a layering separation of the two phases. The light effect is created by a beam of light that is reflected back and forth in a layer. The light beam is slowed down by the additional path and mixed with other light beams so that it emerges from the mineral with a different wavelength. The light effect depends on the thickness and orientation of the layers, and the angle of incidence and viewing angle must also be correct. Labradorite got its name from where it was first found, the Labrador Peninsula in Canada.

Usage:
Because of its beautiful shimmer, labradorite is a coveted gemstone. However, its high sensitivity to the influence of heat, acids and alkalis and galvanic baths makes processing very difficult. Even cleaning in an ultrasonic bath damages the stone.