Among the most precious gemstones on earth, Australian opal is known for its dazzling array of colour and patterns. It is found mostly in Australia and South Australia. The major opal mines are located in Mintabie, Lambina, Coober Pedy, Quilpie, and Andamooka.
The fire opal from Australia is one of the most common varieties of opal. Its body colour ranges from milky white to translucent. It is found in Coober Pedy, Mintabie, and White Cliffs, New South Wales.Black opal is a darker variety of opal. It is mined around Lightning Ridge, New South Wales. It is one of the most expensive gemstones in the world. The black base of the opal is usually a semi-precious stone such as tourmaline or glass. '
They are made up of three layers, each glued to the black base. These layers are covered with a natural crystal cap. They are sold as an affordable alternative to black opal. They are also more resistant to impact than black opal. This makes them a popular choice among collectors. They are sold by carat weight.In addition to Black and White opal, there are two other varieties of opal found in Australia. These are crystal opal and boulder opal. The crystal opal is usually white with color flashes, while boulder opal is a darker variety that occurs in sandstone boulders.These two types of opal are the most common varieties found in Australia. They are mined mostly in outback locations in Queensland and New South Wales.
Mostof original fire opal gemstone is ethically mined by small teams. The mining is done by tunneling, shaft sinking, and open cut. It was once done by groups of people, but today it is done by individuals. The mining methods are still used by aboriginal people.The opal's formation is estimated to have started at least 20 million years ago. It was created as a result of silica-carrying groundwater filling in cracks and voids in the sedimentary basin. Over time the silica gradually hardened into gel, and impermeable barriers trapped the silica-carrying groundwater. The result was a sedimentary basin with small faults and joints, which formed pathways for the groundwater to move.
The water table was close to the surface in central Australia, and was acidic and close to the surface.The formation of the opal was poorly understood. However, the geological history of the basin shows intense weathering. The sedimentary rock in central Australia was organic rich and volcanic in origin. It was subjected to a long sub-tropical weathering regime until about 40 Ma. A rare red layer indicates that gravity played a part in the arrangement of the silica spheres. It is believed that the opal originated in the sedimentary rock in central Australia.
Other varieties of opal include cabochon opal, which features a bright array of colours. These opals are sold as cabochons by carat weight. They are also sold as polished opals. The cabochon opal shows a brilliant array of colours and a strong play of red. At RatanrashiYou can also find a lot of varieties of Fire Opal From Australia - a government gemstone shop online from Meerut.