Opals
Recently, inspired by the colours in the outback opal field paintings of Rowdy Wylie we have been chatting in the Comments box about opals and the brilliant colours they emit.
I am lucky enough to own a black opal ring which belonged to my mother though the setting has had to be replaced with a modern setting. As you can see black opals are not black!!
If we zoom in closer you will see the brilliant array of colours.
So what makes an opal be classified as a black opal?
Black opal is characterised by a dark body tone which can range from dark grey to jet black. However this refers only to the general body tone of the stone, and is not related to the rainbow or spectral colours present in the opal.1
Australian black opal is the rarest type of opal. The majority is found only in one small place in the world and its unique nature of carbon and iron oxide trace elements give it its black body tone. There is simply no other region that produces the same quality as Lightning Ridge.2
Where is Lightning Ridge? About 750 kms from Canberra (the capital city of Australia) and about 715 kms from Sydney in New South Wales. The Ridge as the locals call it, is in northern New South Wales but is only 65 kms from the Queensland border.
You can visit Lightning Ridge by entering the bookmark link below.
Contributors to Wikimedia projects
WHAT MAKES AN OPAL PRECIOUS?
Opals are defined as precious opals (as opposed to common opals) when they display these flashes of vibrant rainbow colours. This optical phenomenon, unique to opal, is called ‘play-of-colour’. The best precious opals display all the spectral colours from red to violet. This is a feature that led the Roman naturalist Pliny the Elder (Ist c. AD) to describe precious opals in his Natural History as if they were all the gemstones rolled into one:
“This most beautiful of gems combines the fire of the ruby, the brilliant purple of amethyst, and the sea-green of emerald; all shining together in glorious and incredible union.”
The beauty and mystery of this optical phenomenon made opals one of the most precious gems in Antiquity and the Middle Ages. They are sometimes referred to as the ‘queens of gemstones’. The fiery and iridescent qualities of opal have inspired poets like William Shakespeare who, in Twelfth night, crafted a metaphor between the fleeting colours of opal – and taffeta- and the changing mind of Duke Orsino:
“Now, the melancholy god protect thee, and the tailor make thy doublet of changeable taffeta, for thy mind is a very opal.”3
WHY ARE OPALS BLACK?
Black opal owes its dark coloration to fine particles in its composition. The nature of these trace elements can vary. Carbon and iron sulfides (pyrite and chalcopyrite) formed microbially during the solidification process are mainly considered as being responsible for the dark colour. The body colour of these opals is dark, ranging from pure black to dark grey or chocolate brown, depending on the environment in which they formed. 3
Check out this great site to learn more about this delightful gemstone.
The Gemmological Association of Great Britain (Gem-A)
Opal is found around the world (Brazil, Mexico, Honduras and the western US) however Australia produces 95% of the world's precious opal and it is our official national gemstone.4
Please follow the bookmark link belong to learn a little more about “The Arts”, poetry, painting, photography and music all of which have been stimulated by our wonderful National Gemstone “Precious opal”.
Anthony Smallwood
Credit
1. opalsdownunder.com.au
2. blackopaldirect.com
3. gem-a.com/gem-hub/gem-knowledge/understanding-precious-black-opal-and-its-properties
4. ga.gov.au/education/classroom-resources/minerals-energy/australian-mineral-facts