The labradorescence of Labradorite
One of my favourite minerals.
Labradorite (Na,Ca)₁₋₂Si₃₋₂ O₈ is a feldspar mineral of the plagioclase series and is treasured for its remarkable play of colour, known as labradorescence or chatoyance.
The stone is composed in aggregate layers that refract light as iridescent flashes of peacock blue, gold, pale green, or coppery red.
The geological area for labradorite is Paul's Island near the town of Nain in Labrador, Canada. It has also been reported in Norway, Finland and various other locations worldwide, with notable distribution in Madagascar, China, Australia, Slovakia and the USA.
This specimen is from Madagascar.
Size: 85mm x 56mm x 18mm
What is Labradorescence?
Labradorescence is not a display of colours reflected from the surface of a specimen. Instead, light enters the stone, strikes a twinning surface within the stone, and reflects from it. The colour seen by the observer is the colour of light reflected from that twinning surface.
What is Chatoyance?
Chatoyance is an optical phenomenon in which a band of reflected light moves just beneath the surface of a cabochon-cut gemstone.