Opal is a non-crystalline form of mineral silica. Opal is related to the more common crystalline cousins such as quartz and agate. Opal differs as it is formed from amorphous lumps of silica rather than that from naturally faceted crystals. The chemical composition of opal is SiO2H2O, silicon dioxide combined with water (an opal stone may contain up to 30% water.) Opal’s Moh’s hardness rating is measured at 6.0 to 6.5 on the scale similar in hardness to quartz. Most opal is more than 65 million to 145 million years old and is found in the Cretaceous layer of rock which was during the period when dinosaurs roamed the earth.
Opal tends to be found near the earth’s surface in areas where ancient geothermal hot springs once flowed. The minerals bubbled up from beneath the surface of the earth and slowly over centuries lined the walls of cavities in the bedrock. More than 90% of the world’s quality gem opals come from Southern Australia, although it can be found in other parts of the world such as Ethiopia, Brazil, Mexico, Czechoslovakia and Nevada. All black opal comes exclusively from Australia.
Amazing Facts About Opals
Opal is the official birthstone for October. Metaphysically opal symbolises purity and hope. It has been regarded as a protective stone, as it keeps the wearer from harm. Opal is a great gift for your loved ones born this month.
The beautiful opal is formed from rain. There is some conjecture on how exactly this precious gemstone forms, but many believe it is formed when water from rain seeps down into crevasses in the rock. Once the water evaporates, the silica that is left behind dries out and hardens into precious opal.
Opal has been found on Mars! It is one of only a handful of gemstones that have ever been discovered outside of our planet (the other gemstone being Peridot that’s found from outer space).
Opallios is the Greek word for Opals meaning To see a change of colour. The Roman word for Opal is Opalus meaning precious stone. The ancient Greeks believed that opals were formed from the tears of joy wept by Zeus when he defeated the titans, and that the opal bestowed prophetic powers.
The ancient Romans considered it a symbol of hope and good fortune. A roman scholar in 75AD summed up our beautiful opal saying: “Some opal carry such a play within them that they equal the deepest and richest colors of painters. Others…simulate the flaming fire of burning sulphur and even the bright blaze of burning oil.” He marveled that this kaleidoscopic gem encompassed the red of ruby, the green of emerald, the yellow of topaz, the blue of sapphire, and the purple of amethyst.” This is why Opal is commonly called the Queen of Gemstones.
Australia produces around 95% of the worlds opals. The majority of this Opal is white Opal from the fields of Coober Pedy in South Australia.
Australian native Aborigines tell us that opal is our creator’s footprint, that touched the Earth at the base of a rainbow to bring harmony.
Opal is a Lucky gemstone. Most civilizations see opal as a lucky stone. There have been some exceptions to this including an English writer in the 1800’s and other gemstone marketers who say Opal is bad luck in their marketing. Maybe they realized opal is the best gemstone on earth and had to discredit it! But this campaign has failed and now Opal is even considered a talisman in some countries and a status symbol to own in others.
Queen Victoria’s favorite gemstone was Opal! She had Sapphires, Rubies and Diamonds from all over the British empire but fell in love with the intoxicating colours of Opals.
The play of color you see in Opal is due to millions of tiny silica Spheres of different sizes. These spheres refract light and cause the beautiful spectral colors you see in an opal. The spheres have to be just the right size and of a uniform nature to create enough color for our eyes to see.