An Opal is a mineraloid gel which is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone, rhyolite, marble & basalt. All naturally occurring opals fall into one of two classes: precious and common. Precious opals are those that display flashes of iridescent colors when turned and tilted, and light strikes its surface at various angles. This effect is called play of color, but is scientifically referred to as opalescence.
The first opals are believed to have been found in Ethiopia around 4,000 BC. The ancient Romans called the opal Ocupid Paederos, which translates to a child beautiful as love. The ancient Romans would grind up and consume opals because they believed they had healing properties and the power to ward off bad dreams. Lets explore three places around the world where Opal originates.
Opals From Australia
In Australia, hydrothermal fluids flowing through rocks deposited silica layers on top of many features, including fossils and simply in gaps in sedimentary sequences. In this specimen now found in the Natural History Museum in London the opal fills cracks throughout the rock, holding it together and giving the full sample an eerie glow.
Australia has to be the most famous of all countries for the precious stone, the opal. It was first found back in the late 19th century, and this was the well- known and well-prized black opal, although there are many different varieties.
The first discovery of common opals in Australia was made near Angaston (SA) by the German geologist Johannes Menge in 1849. Both the Queensland Boulder Opal and Lightning Ridge fields attracted miners in the 1880’s. Production of precious opal began at White Cliffs (NSW) in 1890, from Opalton (Qld) in 1896, and at Lightning Ridge (NSW) in 1905. Today, Lightning Ridge is a popular tourist destination with the annual Lightning Ridge Opal show attracting people from all over the world.
Opals From Ethiopia
Just recently a new discovery of gem crystal and hydrophane Opal was discovered in Ethiopia.
Ethiopian Opal was found in Gondar which was at first called desert Opal but it is from a plateau in the highlands. The main field which is creating a lot of excitement now is from a field called Welo.
In the early 1990’s, a new type of opal was found in Mezezo Ethiopia Africa. This new opal was called Ethiopian Chocolate opal because of the chocolate color found inside the nodule.
These opals are found at Yita Ridge, in the Menz Gishe District of Shewa Province, around 150 miles northeast of Addis Ababa, the capital of Ethiopia.
Opals From Nevada
Hidden in the isolated northwest corner of Nevada, lies Virgin Valley. Despite it’s arid and desolate location, rockhounds and miners from all over the world travel here to search for the beautiful black opal for which this area is famous.
This area is famous for the rare and fabulous black opal, known to occur in only two places on Earth: Virgin Valley, Nevada and New South Wales, Australia. These wonderful specimens flash and gleam with a rainbow of brilliant reds, blues, greens and purples in a jet black matrix. Prime examples can be worth more per carat than even diamonds.
Also found in the area is opal in a variety of colors and types from the famous black opal to the amber colored honey opal, the clear jelly or crystal opal, and the pure white matrix of the lechosos or milk opal, all of which can contain the stunning play of color which signifies the ‘precious opal.’
The Virgin Valley area contains a barely scratched precious opal reserve and resource, and is part of a 68,000 acre area set aside for entry under the general mining laws. The opal-bearing areas are spread out over a large area, but the precious opal occurrences are smaller isolated deposits within the region. Common opal is just that, “common,” and can be found throughout the area, along with petrified wood, agate, and obsidian. Most precious opal producing ground is covered by valid mining claims. Very few of the nearly 200 claims in the Valley actually produce precious opal.