Peridot is the
official birthstone for August as adopted by the American
National Association of Jewelers in 1912. It is also the stone
for the Zodiac sign of Libra. Peridot is suggested as a gem to
give on the 16th wedding anniversary. Peridot is 6.5 - 7 on the
Mohs scale of hardness. Gem quality Peridot comes from Zagbargad
Island in the Red Sea, Myanmar "formerly known as Burma),
Pakistan, Brazil, Germany, Mexico, Australia, Arizona and
Hawaii, USA. The best quality peridot has historically come
either from Myanmar or Egypt but in 1994 a new deposit of
peridot was discovered in Pakistan which produces some of the
finest stones. Large crystals have been found in this area, one
stone was more than 300 carats. The gem material found in
Arizona, which is approximately 85% of the world's production,
is of lesser quality, because it is an abundant source, it is
much more affordable. Large peridots, close to 200 carats in
size, decorate the shrine of the three Magi at the Cologne
Cathedral.
Click here for a picture in natural form.
Click here for more faceted and natural specimens.
Description:
Peridot ranges in color from light yellow-green to the intense
bright green of new spring grass to olive. Because of the way
Peridot splits and bends the rays of light passing through it,
it has a velvety appearance, a rich glow, and a slightly greasy
luster. The purer green a peridot is the higher the value. Any
tinges of brown or visible flaws greatly diminish the price.
Throughout time, Peridot has been confused with many other
gemstones, even Emerald. Many Emeralds of royal treasures have
turned out to be Peridots. And although Peridot is distinctly a
different shade of green, many jewelers refer to Peridot as
"Evening Emerald". Emerald is a dark green as opposed to a
yellow green and always contains inclusions. Other green
gemstones confused with Peridot include Apatite (which is much
softer), Green Garnets (have no double refraction), Green
Tourmaline and Green Sinhalite (both of which are strongly
pleochroic), Moldavites (no double refraction, an unusual olive
green gem that comes from meteorites called pallasites,
Moldavite is found in the Czech Republic and believed to have
arrived from space in a meteor about 14.8 million years ago) and
Green Zircon (significantly heavier). All of these gemstones
rarely have as nice a yellow component to their green color as
does most peridot, but darker green peridot can be confusing
when good crystal form is not discernible. It is not clear
whether the word Peridot comes from the Arabic word "faridat",
which means "gem" or if it is derived from the French word "peritot"
which means "unclear". In the 18th century, the French were the
first to call this yellowish-green stone Peridot. Before this
time, Peridot was called Topaz. Peridot has been mined as a
gemstone for an estimated four thousand years and is mentioned
in the Bible under the Hebrew name of "pitdah".
Chemistry:
Peridot pronounced (pair-a-doe) is the gem variety of the
mineral Chrysolite or Olivine, the formula is written as (Mg,
Fe)2SiO4 to show the substitution of the
magnesium and iron. Olivine, which is actually not an official
mineral, is composed of two minerals: fayalite and forsterite.
Fayalite is the iron rich member with a pure formula of Fe2SiO4.
Forsterite is the magnesium rich member with a pure formula of
Mg2SiO4. Peridot is usually closer to
forsterite than fayalite in composition although iron is the
coloring agent for Peridot. The best colored peridot has an iron
percentage of less than 15% and includes nickel and chromium as
trace elements that may also contribute to the best peridot
color.
The Olivine Group is a term that is sometimes incorrectly
applied to just two minerals that are often lumped together and
simply called olivine. The two minerals are fayalite and
forsterite and are perhaps best referred to as the Olivine
Series. Although olivine is not an official mineral name in
itself, it is a term that is used to denote intermediate
specimens between fayalite and forsterite. The true Olivine
Group is more inclusive and is a group of similarly structured
orthorhombic nesosilicates. The structure of the Olivine Group
is composed of a layered closest-packed oxygen framework with
the silicon ions occupying tetrahedral sites and the metal ions
occupying octahedral sites called M1 and M2 The M1 site is a
slightly distorted octahedron. The silicon tetrahedral sites or
silicate tetrahedrons, SiO4, are not adjacent to each
other and therefore independent to each other making them true
nesosilicates.
These are the members of the Olivine Group:
- Fayalite (Iron Silicate)
- Forsterite (Magnesium Silicate)
- Glaucochroite (Calcium Manganese Silicate)
- Kirschsteinite (Calcium Iron Silicate)
- Laihunite (Iron Silicate)
- Liebenbergite (Nickel Magnesium Silicate)
- Monticellite (Calcium Magnesium Silicate)
- Olivine (Magnesium Iron Silicate)
- Tephroite (Manganese Silicate)
Legends, Myths and Healing
Properties:
 Peridot
gems were probably used in the fabled Breastplates of the Jewish
High Priest and historical legend says that Peridot was the
favorite gemstone of Cleopatra, although at the time they were
called Emeralds. It is thought to bring the wearer good luck,
peace, and success. Its powers include health, protection, and
sleep. The advantages of Peridot are to attract love and calm
anger while also soothing nerves and dispelling negative
emotions. Peridot is considered a tonic for the whole body and
protects the wearer from negativity. It is associated with
stress reduction and relaxation. Egyptians used Peridot to clean
and heal the heart. Powdered Peridot has been used to cure
asthma and a Peridot placed under the tongue of someone in the
grip of a fever is said to lessen his or her thirst. Legend has
it that drinking from a Peridot goblet can increase the potency
of medicines. |
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