Skip to main content

Centenary of the Australian opal: the rainbow effect


A hundred years ago, on May 8, 1915, the first piece of opal was found in Australia. Willie Hutchinson was prospecting for gold with his father in a desert town called Coober Pedy when he found a few pieces of whitish iridescent rainbow-coloured stones. Coober Pedy is now the “opal capital of the world.” It produces 80% of the world’s opals (BBC, May 8, 2015).

A group of international geologists hope to legally define the opal, Australia’s national gemstone, as a Global Heritage Stone Resource (GHSR) in order to recognize and preserve the opal’s significance in human culture. No stone has yet been designated a GHSR status.

Initially the geologists wanted to recognize specific construction rocks, such as Portland stone, Carrara marble, Sydney sandstone, and Norwegian larvikite. They want to designate and protect particular stones and rocks for conservation. But when the opal was added to the list, it was a controversial decision, even amongst geologists. Some stated that opal was not a construction stone because it was processed as jewellery.

The centenary of opals aims to highlight the magnificence of their geological context. They result from the Eromanga Sea that covered central Australia about 100 million years ago – it was the great central sea. Opals in Coober Pedy are derived from sedimentary effects. Acidic fluids dissolved silica from sandstone rich in quartz, which gives the stone iridescence – a rainbow effect. Opals found in other locations originate from volcanic events, not sedimentary settings.


The Global Heritage Stone Resource project commenced in 2008. The project has not yet designated its first status to any stone – but the honour is likely to go to Portland stone, the cream coloured building limestone found in quarries in Dorset on the south coast of England. St. Paul’s Cathedral and Buckingham Palace in London are constructed from Portland stone, and so is the United Nations building in New York. So the opal, a controversial choice, may take another hundred years before it makes the GHSR status as a heritage stone.





MARTINA NICOLLS is an international aid and development consultant, and the author of:- The Shortness of Life: A Mongolian Lament (2015), Liberia’s Deadest Ends (2012), Bardot’s Comet (2011), Kashmir on a Knife-Edge (2010) and The Sudan Curse (2009).
Labels:

Comments

Post a Comment

Popular posts from this blog

Pir-E-Kamil - The Perfect Mentor by Umera Ahmed: book review

The Perfect Mentor pbuh  (2011) is set in Lahore and Islamabad in Pakistan. The novel commences with Imama Mubeen in medical university. She wants to be an eye specialist. Her parents have arranged for her to marry her first cousin Asjad. Salar Sikander, her neighbour, is 18 years old with an IQ of 150+ and a photographic memory. He has long hair tied in a ponytail. He imbibes alcohol, treats women disrespectfully and is generally a “weird chap” and a rude, belligerent teenager. In the past three years he has tried to commit suicide three times. He tries again. Imama and her brother, Waseem, answer the servant’s call to help Salar. They stop the bleeding from his wrist and save his life. Imama and Asjad have been engaged for three years, because she wants to finish her studies first. Imama is really delaying her marriage to Asjad because she loves Jalal Ansar. She proposes to him and he says yes. But he knows his parents won’t agree, nor will Imama’s parents. ...
1 comment
Read more

Sister cities discussed: Canberra and Islamabad

Two months ago, in March 2015, Australia and Pakistan agreed to explore ways to deepen ties. The relationship between Australia and Pakistan has been strong for decades, and the two countries continue to keep dialogues open. The annual bilateral discussions were held in Australia in March to continue engagements on a wide range of matters of mutual interest. The Pakistan delegation discussed points of interest will include sports, agriculture, economic growth, trade, border protection, business, and education. The possible twinning of the cities of Canberra, the capital of Australia, and Islamabad, the capital of Pakistan, were also on the agenda (i.e. called twin towns or sister cities). Sister City relationships are twinning arrangements that build friendships as well as government, business, culture, and community linkages. Canberra currently has international Sister City relationships with Beijing in China and Nara in Japan. One example of existing...
2 comments
Read more

The acacia thorn trees of Kenya

There are nearly 800 species of acacia trees in the world, and most don’t have thorns. The famous "whistling thorn tree" and the Umbrella Thorn tree of Kenya are species of acacia that do have thorns, or spines. Giraffes and other herbivores normally eat thorny acacia foliage, but leave the whistling thorn alone. Usually spines are no deterrent to giraffes. Their long tongues are adapted to strip the leaves from the branches despite the thorns. The thorny acacia like dry and hot conditions. The thorns typically occur in pairs and are 5-8 centimetres (2-3 inches) long. Spines can be straight or curved depending on the species. MARTINA NICOLLS is an international aid and development consultant, and the author of:- Similar But Different in the Animal Kingdom (2017), The Shortness of Life: A Mongolian Lament (2015), Liberia’s Deadest Ends (2012), Bardot’s Comet (2011), Kashmir on a Knife-Edge (2010) and The Suda...
1 comment
Read more