Opals of Australia, discover the different types of Opals and the Australian deposits
The different Opal deposits in Australia
The quality and quantity of Opals available on the Australian continent make it the world's largest producer for over a century. In July 1993, Opal was proclaimed Australia's "national gem". Mainly sedimentaryAustralian Opal has the reputation of being the most stable and valuable on the market.
From Coober Pedy White Opals at Lightning Ridge Black Opals through the Queensland Boulder OpalsAustralia has the greatest diversity of Opals and the most famous deposits in the world.
Map of the most famous Opal deposits in Australia | Image credit: ©Charlie's Gems
Boulder Opal is found exclusively in the state of Queensland, in the North East of Australia. They are veins of Opal (silica) formed in the cracks and cavities of a iron matrix (iron-rich sedimentary rock). It is nicknamed "The Stone of the Aborigines", in reference to its unique landscapes reminiscent of Aboriginal Art.
Boulder Opals - Queensland, Australia | Photo credit: ©Charlie's Gems
The Queensland Opal fields extend for several hundred kilometres from Winton to Yowah. This area is called the "Winton Formation". The conditions of extraction are difficult because of the heat and the great dryness.
Here is a list of Queensland's famous Opal fields:
- Winton Winton is one of the oldest deposits in Queensland. Boulder Opals are naturally stable and brilliant.
- Opalton: located 120km from Winton, Opalton was once one of the largest and most heavily mined sites. The area attracts many tourists who come in the hope of finding Opal samples on the dedicated digging area or on the old claims.
- Jundah: this deposit produces different types of Opals: Black Opal. Crystal Opal and Boulder Opal. The Jundah Black Opals were discovered about ten years before the Lightning Ridge Opals.
- Quilpie: it is known as the "Opal City" or the "Home of the Boulder Opal" because of the large amount of Boulder Opal mined in this area. A public digging area allows visitors to freely prospect for Opal fragments.
- Yowah: the Yowah Opal field was already being exploited in 1880. The famous "Yowah nuts" were prospected there. These nodules of ferruginous rocks measuring from 5mm to 20cm contain Opal of a great quality.
- Koroit: discovered in 1897, the Koroit Opal field is one of the most popular in Queensland. Opals from this area have a very hard and lustrous iron matrix. Koroit nuts are also highly prized by collectors.
Boulder Koroit Opals - Queensland, Australia | Photo credit: ©Charlie's Gems
Other examples include Longreach,Kyabra-Eromonga,cunnamulla,bulgarooortoompineamong the most productive fields of the state of the queensland.
operating medium:mainly open-air mines
Find video opale boulder - queensland, australie video credit: ©Charlie's gems
the opals of the south australia
the opals of coober pedy
Find Photo Credit: ©Charlie's gems
coober pedy is a city located in the southern desert of Australia, halfway between adelaide and alice Springs. The first opal was discovered in 1915 by Willie hutchinson, a 14-year-old teenager whose father was part of a group of gold prospectors (new colorado prospecting syndicate). the field of Pale, initially known as "Stuart range opal field", was exploited shortly afterwards. Aborigines renamed him “Coober Pedy” in 1920, which can be translated into “white man in a hole”. this appellation refers to the dozens of white men who arrived on site to dig the mines of Pales and their homes. Indeed the unsustainable heat forced them to build their houses under the earth (troglodyte dwellings). tourists passing to coober pedy can visit the manyunderground facilities(church, shops, hotels, bars). andunderground minesto admire the beautiful walls of Opales.
the beautifulwhite milky opalsof coober pedy prospect in depth in the layers of sandy clay deposited by the shallow sea that covered the territory 100 million years ago (Cretace era).
extraction conditions are extremely difficult and costly and the use of explosives is inevitable due to the hardness of the rock. Thousands of holes have been dug over hundreds of square kilometres and mounds of land are visible to loss of sight.
means of operation:tunnels
also includefossil fuels,shells,brachiopodsor anyopalized belemnite rosesin the opal field of coober pedy.
Find Belemnite rostre opalized - coober pedy, australie credit photos : ©Charlie's gems
♪Belarusaremarine cephalopodshaving lived up to the Cretaceous era 100 million years ago (an ancestor of the seiche). therostremeans the inner bone of the belemnite in the form of a “gun ball”.
These shellfish lived at the time in the old sea that covered the area or is coober pedy, in southern France. When the sea turned back, the shells buried in the layers of sandy clay. Only 20-30 million years ago, the pressure and variation of the napples led to the deposition of Palae while fossils were covered by silica saturated liquids.
Brachiopode opalisé - coober pedy, australie |MISUMI
♪brachiopodsaremarine animals with limestone shells bivalves(of which the shell consists of two valves). these specimens are old182 million years(toarcian, lower Jurassic).
process of Palizing a pedy coober shell in australia:
- about 150 million years agothe closed shell was buried in clay sediments. Subsequently the pressure increases due to sediments that accumulate over (the shell does not contain sediments).
- 30 to 90 million years agothe carbonates dissolve and the increase in pressure generates silica enrichment thanks to groundwater rich in dissolved silica.
- about 20 to 30 million years agovariations in the napps produce a deposit of Pale while the shell is covered by the saturated silica fluids. the opalization/silicification process was rather rapid (a few decades only, according to eckert’s experiences, 1977).
Andamooka deposit is located in the south australia desert at 480km of coober pedy. Andamooka’s opals are appreciated for their color lights and the size of the specimens, which in particular make sculptures.
most of Andamooka’s opals are porous and suffer fromtreatmentwith sulphuric acid and sugar to fill the cavities and imitate black opals. they are easily distinguished by their low density and black tasks.
Find Photo credit: ©marine bouvier, gemmologist
operating medium:mainly tunnels
opals found in mintabia can be white, crystal, dark or black, without matrix. the hardness of the rock makes prospecting very difficult. the field of Pales delambina, located 90km from mintabia, was exploited during the decline of mintabia deposit.
means of operation:careers, open pits
the opals of the new south wales
L’Opale noire de lightning ridge
discovered in 1905 by kangaroo hunters, the Black Pale of lightning ridge is one of the most rare and expensive opals on the market. its coloured lights, its patterns and its grey to black body make it an exceptional opal.
Black Opal and Grey Opal - Lightning Ridge, Australia | Photo credit: ©Marine Bouviergemmologist
Transparent to opaque, Black Opal owes the dark color of its base (potch) to the presence of carbon andiron oxide. The term Potch refers to a Common Opalwith no colors. Lightning Ridge Opals are not considered Black Opals.
When it is transparent it is called Opal crystal because the body is dark despite the absence of a black base.
Crystal Black Opal - Lightning Ridge, Australia | Photo credit: ©Marine Bouviergemmologist
The quality and price of a Lightning Ridge Black Opal is determined by 4 main criteria:
- Shine from 1 to 7 (1 being the brightest)
- The color of the base : from N1 to N4 for Black Opal and from N5 to N7 for Dark Opal (N1 being the darkest colour)
- Reasons: harlequin, chinese writting, broad flash, ribbon mackerel, clover leaf... (harlequin being the rarest)
- Color: red is the most popular colour, followed by orange, green and blue.
Lightning Ridge is a great paleontological site where we also find a great diversity of opalised fossils Belemnites, shells, mollusks and more rarely dinosaur vertebrae, shark teeth, fish, turtles and sometimes even crocodile bones or frog jaws.
The deposit produces less and less each year, which explains the constant rise in prices for quality parts.
Means of operation : mainly wells
White Cliffs Opals
Opal prospecting in the White Cliffs area began in 1890. This is the only place where the famous "Pineapple Opals" or "Pineapple Opals"These are highly sought after by collectors because of their rarity. It is in fact a pseudomorphosis Glauberite (calcium and sodium sulphate) or Ikaite (calcium carbonate) crystals aggregates have been replaced by Calcite and then by Opal. There are also some specimens of fossil woodsandopalized shellsof good quality.
operating medium:mainly wells
the fire opals of the Western Australia
williams opal mine(three mile hill mine) is a recently discovered Opale deposit in the area ofcoolIn the Western Australia. This is the only deposit of Pale in this vast state of 2.646 million km2. Originalvolcanic, it has golden yellow colours with oranges similar to Mexican opals. its brilliance and hardness allow it to be sized in facets. it is prospected only a few dozen centimetres from the surface. The Australian Fire Opal was presented in 2014 at the International Tucson Minerals Fair in Arizona.
fire opal, australia western ©TucsonShow
the price of Australian opals
the criteria that determine the price of an opal
the value of an opal is determined according to several criteria:
- the color:red is the most rare and coveted color. orange, yellow, green, blue and purple
- games and color patterns:pinheads, ribbons, flashes, puzzles, straws, arlequins.
Find Australian white opal pattern arlequins photo credit : ©marine bouvier, gemmologist
- the shine:brilliance and color intensity
- thicknessof the opal layer
- the type of opal:black, crystal, white, milky, boulder, fossil.
- polishing quality:finishes, stripes, impacts, natural cavities.
- the shape:Oval, drop, free, calibrated cabochon.
- purity:presence of inclusions
- the source:the deposit, the locality
- the nature of the opal:natural, treated or glued (double, triplets)
other factors that influence the price of opals
other factors also contribute to the increase in the price of malaria:
- extreme conditions of extraction according to deposits
- the cost of concessions and equipment
- The increase in fuel and machinery prices
- Government restrictions
- the consequences of the current health crisis
- Customs import regulations
the price also varies depending on the supply and demand. when the supply is low and the demand continues to increase, as is the case with the pandemic in particular, then the price increases.
the regulations of the australia opal prospecting
Opal’s prospecting is a highly regulated activity in australia. minors and prospectors must be provided withlicencethe cost, period of validity and modalities differ in each state. The exploitation of certain deposits requiresauthoritiesspecific orpurchase of a concessionfor a specified period. Other fields are free to access with or without a license, provided you use manual tools and no machine. it is also sometimes possible to look for fragments of opals on the old concessions now public. concerning explosives,restrictionshave recently been established to regulate and reduce this practice.
the treatments, doublets and triplets of Pales
What treatments can Australian opals be treated?
there are treatments forsolidifierorstabilizationopals when the matrix is sandy or porous, such as andamooka specimens. one can quotesugar treatmentand tosulphuric acidFor example.
in some cases opal cracks are combined withresin,siliconeor sometimes withoilbut this method is only temporarily effective.
Charlie’s gems offers only natural opals, without collage or treatment.
What is a doublet and a triplet of Pale?
thedoubletmeans a piece of Opal stuck on a dark base or a piece of natural rock (2 layers.)
Find opale doublet, australie photo credit : ©marine bouvier, gemmologist
onetripletmeans a piece of Opal glued on a dark base to which a quartz cap or dome-shaped resin is added on the top (3 layers. )
image credit : ©Charlie's gems
These collage methods allow to market small fragments of Opals too thin, too fragile or invendable in the state. The aim is to protect the thin layer of Opal while accentuating the colour lamps. opals from these processes are so-called composite stones. certain doublets or triplets are so well realized that it is difficult to detect it with the naked eye, so you have to remain vigilant and ask the seller in case of doubt.
Opales’ research program (outback opal Hunters) on rmc discovery
broadcast in more than 100 countries, this program launched in February 2018 enabled millions of people to discover Australian opals and mining conditions. the principle of the program is to follow the adventures of 6 teams of prospectors in the most famous fields:coober pedy, Lightning Ridge, Opalton,yowah,white cliffsormintabia. The team “The fire crew” has helped to bring the Australia Western Fire Opal to the public.
Find the fire crew cassidy ricketts ' adam piromanski credit photo: ©Supplied
symbolic, legends and virtues of the Palestinian
the symbol of the Palestinian
The Opal is the stone associated withmonth of Octoberand21st wedding anniversary. it symbolizes light, harmony. purity, hope and luck.
legends and myths around the Pale
the opal, a sacred stone
The Pale is a sacred stone in the eyes ofaborigines, who think that the Pale was created during the visit of the divinity at the origin of their incarnation. according to their legend she descended on earth in the form of a rainbow, and transformed the rocks into shining opals. the aborigines nickname the Palae "Archi-en-ciel snake".
the opal was always considered alucky charm. ♪RomansandGreekThought she brought luck, wealth and insight. enindeIt embodies trinity: Brahma, vishnu and shiva. eneuropeit symbolizes good fortune and prosperity.
Opal brings bad luck? Superstitions and legends
On the contrary, some believe that Opal jinxparticularly since the publication of Walter Scott's novel entitled Anne of Geierstein in 1829. In this story the princess wore an opal in her hair that changed colour according to her mood. When holy water touched the stone, it turned black and the princess fainted before turning to ash. The publication of this novel caused Opal's sales to drop by half for a time.
The diamond sellers also contributed to maintain this legend of "the cursed Opal" at the beginning of the last century. Indeed the Opals gaining in popularity, the diamond dealers were afraid that the Diamonds were devalued or forsaken in favour of the Opals. They then spread the rumor that a cracked Opal would bring bad luck.
The virtues of Opal in lithotherapy
Related to the crown chakraOpal is considered to be a protective stone which facilitates the meditationIt regulates moods and stimulates creativity. According to beliefs, it develops intuition and the clairvoyance and promotes connections with spiritual beings and the subtle planes.
Recharging and purification
Here is a table listing the different recharging and purification methods minerals click here.
The different types of Opals in the World
An article on the Opals of the World is in progress.