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Where Zanzibar's Opals come from
Zanzibar's opals are boulder and solid light opals from Queensland and Coober Pedy in central Southern Australia.
Although there are lots of opal
mining towns in Australia there are four which have become household names -
Coober Pedy, Andamooka, White Cliffs and Lightning Ridge. They are wild and
unruly places surrounded by a moonscape of mullock humps where people fight
against horrendous climatic conditions in their search for precious gemstones.
They are, as one observer noted 'monuments to the tenacious optimism of all
mankind'.
Currently, Australia produces around 95% of the world's opal for use in the
jewelry industry. Other countries in which opal is found in small amounts
include Honduras, Mexico, former Czechoslovakia, United States and Brazil,
however these types of opal often differ in appearance.
Australia's Opal fields lie in the three states of Queensland, New South Wales,
and South Australia, along the site of the ancient 'Great Inland Sea', or 'Great
Artesian Basin'. Solid Light opal is found in South Australia, Black opal
is found in Lightning Ridge, NSW, and 'Boulder' opal is found in Queensland.
There is an Aboriginal
explanation for the opals in these areas. According to legend a huge wheel
of fire fell to earth and sprayed the countryside with brilliant colored stones.
These opal mining areas lie in part of the vast Great Australian Basin. The
Great Australian Basin covers over one million square miles of eastern
Australia. It was formed when the sediments of the Basin lay at the bottom of a
large inland sea. It is these sediments that later hosted the formation of
precious opal.
The sedimentary host rocks are essentially horizontal. This is because
they were deposited on the floor of the inland sea and have not been deformed.
The rocks which host the opal were deposited in shallow water near the edge of
the Basin, probably in an estuary. This period of formation happened 50-65
million years ago.
Overlying the Cretaceous sedimentary rocks are sandstones and conglomerates that
were deposited by streams and rivers in the Tertiary period, about 15 million
years ago. Many of these younger rocks have hardened to form silcrete and are
often quarried for road materials.
"Opal Capitol of the world"
Coober Pedy (28°56′S 134°45′E),
population 3,500, is a small town in South Australia, 526 miles (846 kilometers)
north of Adelaide on the Stuart Highway. The town is known as the opal capital
of the world because what are widely regarded as the most precious opals are
mined there. All of the Australian Opal
Jewelry that Zanzibar Tribal Art sells come from this area of Australia.
The name 'Coober Pedy' comes from the local Aboriginal term
kupa piti,
meaning "white man in a hole" or "white man digging a hole".
Located in the Australian outback, Coober Pedy is hundreds of miles from the
nearest settlement. The harsh summer temperatures and severe sand storms
necessitate that most residents live in caves bored into the hillsides and work
underground in mine shafts. A standard three bedroom cave home with
lounge, kitchen and bathroom can be drilled out of the rock in the hillside for
a similar price to a house on the surface. These underground homes remain
at a constant temperature whereas surface living needs air-conditioning,
especially in the summer months when the temperature can exceed 120 degrees
Fahrenheit. Relative humidity rarely gets over 20% on these hot days and
the skies are often cloud free so its a "dry heat". Reminiscent of the
painted desert of Arizona, USA, this is a desolate and unforgiving place.
Opal mining is extremely tough
work. Claims are aggressively guarded and it is back and mind breaking
work. Consider that during much of the last decade there was a drought -
and water had to be trucked in from hundreds of miles away (and its not free) -
plus if you want electricity you often have to use a generator (and fuel isn't
free, either!). Miners often go decades if not a lifetime without even
breaking even - all hopeful of striking it rich.
Some of the interesting attractions in Coober Pedy include the mines, the
graveyard and the underground churches. The first tree ever seen in the town was
welded together from scrap iron. It still sits on a hilltop overlooking the
town. The local golf course is completely free of grass and golfers take a small
piece of "turf" around to use for teeing off.
Coober Pedy is a popular tourist destination and the surrounding countryside
(such as the Breakaways and Moonplain) have been featured as backdrops in films
including Mad Max Beyond Thunderdome, Priscilla, Queen of the Desert,
and Pitch Black. Coober Pedy was also recently featured in the
second season of The Amazing Race.
"Where
Boulder Opals come from"
Queensland produces Boulder
Opal, an unique type of opal which is found attached to a host rock, ironstone.
Much opal mining in Queensland is carried out in 'open cut' mining operations
(shown left).
The Queensland opal fields are within a belt of deeply weathered Cretaceous
sedimentary rocks known as the
Winton Formation, which extends in a north-westerly direction from the New South
Wales border at Hungerford stretching west of Cunnamulla, Quilpie, Longreach and
Winton to Kynuna, a distance of about 650 miles.
Queensland's opal mining fields are located in the west and southwest of the
State, and include Yowah field (which includes Black Gate ), Koroit field,
Toompine field (includes Lushingtons, Coparella, Duck Creek, Sheep Station Creek
and Emu Creek fields ), Quilpie field (includes some of the more productive
mines in recent times - Pinkilla, Bull Creek, Harlequin , and probably the most
famous mine of all, the Hayricks ), Kyabra-Eromanga field, Bulgroo field
(includes the Bulgroo , or German's and to the north, Budgerigar ), Yaraka field
(includes the mines in the Macedon Range, such as Mount Tighe), Jundah field
(includes the Jundah and Opalville mines), Opalton-Mayneside field (centred on
the old abandoned township of Opalton and to the south in the Horse Creek -
Mount Vergemont area), and Kynuna field.
Boulder opal is widely distributed in rocks in these areas, in generally
elongated or ellipsoidal ironstone concretions or boulders, from a few
centimeters, to up to 3 m across.
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