| All
of Nature’s splendour seems to be reflected in the manifold opulence of fine
Opals: fire and lightning, all the colours of the rainbow and the soft shine of
far seas with fiery sparks that dance through it as the stone is moved. Numerous
legends and tales surround this colourful gemstone, which can be traced back in
its origins to a time long before our memory, to the ancient dream time of the
Australian aborigines. It is reported in their legends that the creator came down
to Earth on a rainbow, in order to bring the message of peace to all the humans.
And at the very spot, where his foot touched the ground, the stones became alive
and started sparkling in all the colours of the rainbow. That was the birth of
the Opals A
good and colorful opal usually contains 4 to 5% water, but some may contain up
to 30%. If there is over 20% of this trapped water, it will cause cracking and/or
crazing, just like when water leaves mud. These precious stones are formed from
lumps of silica and are actually silicon dioxide and water. The water in the stone
cannot escape unless the opal is heated to extreme temperatures. Most
opals are more than 60 million years old and are typically found where hot springs
once flowed. The silica in the springs lined the walls of cracks, vents, and cavities
in the bedrock. When the hot springs dried up, the silica hardened into opal.
An opal has an extraordinary ability to refract light and reflect specific wavelengths
of light. This capability is so unique that the term "opalescence"
was coined to describe it. Each tiny sphere of silica within an opal refracts
a single pure spectral color depending on the size and spacing of the sphere.
Looking at an opal can be like looking at water droplets in a rainbow. Up
to the first half of the 19th century, opals were relatively rare. But then their
career boomed suddenly and made them one of the most popular gemstones. In the
era of Art Deco opals experienced their flourishing, with contemporary gemstone
artists preferring them to all other stones because of their subdued charm, which
in turn was excellently suited to be combined with enamel, another very popular
material of those days. Opals
are considered to be very magical. They are reputed to have healing powers and
are used for various rituals. Wearing a black opal near the heart is said to ward
off evil and protect travelers. Arabs believed that opals have a fiery color because
they fell from heaven in flashes of lightning. Opals were set in the crown of
the Holy Roman Emperor and in the crown jewels of France, and it is said that
Cleopatra wore an opal to attract the gaze of Mark Antony. The
opal has been mined for centuries, at least since Roman times when they extracted
the opal from areas now within the Czech Republic. Archeologists have found 6,000-year-old
opal ornaments in African caves. The Aztecs made use of local Mexican sources
as did the Spaniards when they exported the material back to Europe. Although
opals are found in Brazil, Indonesia, Canada, Ethiopia, Austria, Honduras, Mexico,
Nevada, Idaho, Oregon, and Mojave, 90% of the world's gem-quality opals come from
southern Australia and ALL black opals come from Australia. The
history of Australian Opal began millions of years ago, when parts of Australia
were covered by a vast inland sea, and stone sediment was deposited along its
shoreline. When the water masses flooded back, they flushed water containing silica
into the resulting cavities and niches in the sedimentary rocks, and also the
remains of plants and animals were deposited there. Here are some interesting
Australian
Opal Facts & Myths. Australia's
lost sea is the only place in the world known to harbor animal fossils in the
opal. It is extremely rare for conditions to be right for formation of fossils;
and even more rare for opalised fossils to form. Usually, only the hard parts
of living things fossilize — for example seed pods, wood, teeth, bones and
shells. This often happens after the plant or animal (or a part of it) is buried
in sand or other sediments that slowly turn to stone. Some
scientists think opalised fossils (and other opal) took thousands of years to
form, at high temperatures and under great pressure; others think opal formed
quickly, at about 20 degrees Celsius. Opalised fossils formed when animal or plant
parts entombed in stone were replaced by silica, in the form of opal. Opalised
bones, teeth, shells and pine cones are rare and dazzling reminders of a time,
110 million years ago, when dinosaurs and other strange reptiles ruled the land,
waters and skies around a great inland sea covering nearly one third of Australia.
Pieces
of dinosaur eggshell and even an imprint of dinosaur skin have been found preserved
in opal. And - very occasionally — an ancient trail of dinosaur footprints
is found marching, ghost-like, across the sandstone roof of an opal mine. Dinosaur
teeth, bones and claws are among the most exciting of opalised fossils. Plesiosaurs,
pliosaurs and ichthyosaurs were swimming reptiles that lived in Australia's inland
sea. They were streamlined fish-eaters — the ancient reptile world's equivalent
to dolphins. Their opalised bones and teeth are found at opal fields such as Coober
Pedy, White Cliffs and Lightning Ridge. Lightning
Ridge in northern New South Wales produces opalised fossils of a variety of dinosaurs
including small, fast-moving carnivorous dinosaurs; large, plant-eating sauropods;
and agile, long-legged hypsilophodontids that cropped plants with sharp beaks.
Dinosaur fossils are rare in Australia and the opal fields are an invaluable source
of information about what the world was like when dinosaurs ruled the land.
From
LostSeaOpals.com
(Contributed by Diane in New South Wales, Australia) |
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