by Nasrina Parvin Khan
Labradorescence is an exclusive optical phenomenon that has solely shown by the feldspar gem Labradorite in this earth.
Iridescence flashes of colors, which appear on the surface of the labradorite feldspar is known as Labradorescence. Labradorescence is an exclusive optical phenomenon that has solely shown by the feldspar gem Labradorite in this earth. This phenomenon like, Adularescence of moonstone with more attractive bluish color. The iridescent display on the surface of the gem especially directional oriented.
Image courtesy Mineralminers.com
Labradorite changes color with its every position, which is usually available in glittering pastels and deep gold colors. The bright and beautiful display of Labradorescence can be change with movement of the stone. The “shiller” would be vanishing temporarily when the stone turned to a different angle. But it comes back again with movement of the gem in another direction.
One or more colors can be seen on the surface of the gem by this special optical phenomenon. A bluish sheen with a colored flash exhibits by this phenomenon. But the bluish flash of Labradorescence is more common. Sometimes greenish, purplish, gold and yellowish reddish bronzy flashes can be seen. Red-orange or peach-orange and white or off-white hues also seldom appear, when the stone is moved under a source of light.
Bright metallic looking spectral colors create on the surface of the Labradorite with the movement of the stone. This colors compares with the wings of tropical butterflies.
Labradorite is also known as “Black Rainbow” in India for its astonishing rainbow colored reflection. Large quantities of translucent white Labradorite can be found in this country. This stone is also called “firestone” because of its rainbow colored sheen.
The structural pattern of Labradorite is the reason of the phenomenon “Labradorescence”. Iridescent effect in Labradorite caused by repeated, microscopic thin layer (lameller) twinning inclusions made-up of black magnetite or ilmenite and generally showing some fracturing. Due to this structure interference and diffraction of light occurs, when it passes through the stone and reflects from the parallel surfaces.
The “shiller” of Labradorite visible at certain angles. No effect is seen when the angles of light faces no thin layer. Some faces of the gem show the silvery or bluish “shiller” this effect will display in cabochon cut gem (tall, domed shaped gem is called cabochon).the colors to be seen on the surface of the gem is also depends on the thickness and uniformity of the layers.
The special optical phenomenon “Labradorescence” named after the mineral “Labradorite”, which distinctly posses the phenomenon.
On the other hand the name “Labradorite” derives from the Labrador Peninsula (now part of Newfoundland and Quebec Provinces, Canada), where it was first discovered by a Moravian missionary on the Isle of Paul in 1770. This sodium rich feldspar is also found in Australia, Madagascar, Russia, Mexico, China, India, the Scandinavian Peninsula and the United States etc.
The brightest and most uniform color flashes, without “dead” areas determine the values of the gem. The most valuable deposit of Labradorite is Spectrolite. This particular colorful deposit of Labradorite was discovered in Finland. It shows not only bluish, but also green, gold and rarely red or violet sheen and has been given the name “Spectrolite” for its similarity to the color spectrum. “Spectrolite” is the national stone of Finland. It is said to be that it reflects the colors of the nature of Finland.
The background color of the Labradorite is unattractive just like dark smoky gray. The gemstone best esteemed when viewed from different angle and the magical effect of “Labradorescence” observed. Different colors may display or a range of all colors can be visible at the same time due to this phenomenon and added an attraction.