Rockhounds have been flocking to the Virgin Valley to dig up precious black opals since the early 1900s. You can do the same when you pay a visit to Bonanza Opal Mine near Denio, Nevada. Surrounded by wide open spaces and rugged scenery, the opal mine is as remote as can be. However, it's SO worth the journey.
Doublets and triplets usually look darker and more opaque than real opal as they have a non-opal layer attached to the back. Solid natural opals, in contrast, are transparent or white. From a side view, a real opal should look solid. Doublets and triplets, however, will look layered.
The Kern County mines are the only known sources of gem-fire opals in California, and one of only three recognized opal fields in the United States.
Thundereggs are valued between $1 and over $ 100 per slice or cabochon.
Australia's Opal fields lie in the three states of Queensland, New South Wales, and South Australia, along the site of the ancient 'Great Inland Sea', or 'Great Artesian Basin'. White, or 'Milky' opal, is found in South Australia, Black opal is found in Lightning Ridge, NSW, and Boulder opal is found in Queensland.
Opal is a non-crystalline form of mineral silica. 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 is found as two types: volcanic opal which infills vesicles and cracks in igneous rocks, and the more familiar sedimentary or sandstone type which is found in Australia's main fields. Most deposits in other countries are volcanic opal, much of which is prone to crazing.
“That opal actually glows in the dark – the darker the light, the more colour comes out of it, it's unbelievable.” John Dunstan told ABC. Opals are a form of amorphous hydrated silica with up to 20% water locked within the silica structure.
Black opals are mostly mined in Lightning Ridge, in northern New South Wales. Lightning Ridge is famous for the black opal and hundreds of millions of dollars worth of black opals have been found there.
It's believed that perhaps 30 million years ago, lots of silica was released into a solution which filled cracks in the rocks, layers in clay, and even some fossils. Some of them became precious opals. It takes about 5 to 6 million years to make a 1 cm opal to mature.
Generally opals with a black or dark body tone are more valuable than those with a white, light, or crystal body tone, because a stone with a darker body tone tends to display colours more vibrantly. Above – AOGIA 1-9 body tone scale. Black opal is the most prized opal and may realise prices over AUD $15,000 a carat.
Yes from mid march to mid october is about 7 months, Longer if the weather is nice!
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.
Black Opals from Lightning Ridge are considered by many to be the best gemstone investment. This is due to rarity of the opal and the extreme rarity of the bright red fire patterns and high cabochon. Boulder Opals with spectacular colours are also a good investment.
Determine the quality of the opal.To judge an opal, consider its play of colour, body tone, brilliance, pattern, the thickness of the colour bar, and any faults such as cracks or inclusions (natural inclusions are acceptable but never buy an opal that's cracked).
Opals with a very white body tone also tend to have very pale colour. However, good quality white opal can be incredibly beautiful, and may fetch prices up to AUD $200 per carat. There are many factors including brightness and pattern which determine the overal value of opal.
Black opals are exceptionally rare in that they are known to form in only one place: Australia. While Australia makes up 90% of the world's opal market, mining these gemstones ethically and responsibly is extremely important due to their rarity.
Ethiopian opal is one of the most diverse and spectacular types of opals on the market today. This pattern is very rare in any other type of opals. These honeycomb shapes are also known on occasions to have brighter or different colour than the surrounding opal, this is also a rare occurrence in nature.
The “Olympic Australis” is reported to be the largest and most valuable gem opal ever found. It was found in 1956 at the famous “Eight Mile” opal field in Coober Pedy, South Australia. A miner working his claim found the opal at a depth of 30 feet.
The largest and most valuable single piece of rough gem opal is the Olympic Australis, a 3.45-kilogram, 17,000-carat stone estimated to be worth about $1.9 million.
Solid opal should be cleaned gently with mild detergent in warm water and a soft toothbrush or cloth. Avoid bleach, chemicals and cleaners. Doublets & triplets may be wiped with a damp soft cloth and mild detergent, but should never be soaked or immersed.
