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Labradorescence
By: Nasrina Parvin Khan
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
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.
Labradorescence phenomenon
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.
More Resources
Labradorite
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