Opal On Mars, Is It True
That the finest opals on our planet are GAB area of Australia is no secret. For the gemstone enthusiast, it might be clearer if we said that, some of the world's finest opals are mined in the region between Coober Pedy and the Lightning Ridge locality of Australia. Geologists refer to the geographical formation in this areas as the Great Artesian Basin (GAB). The more interesting thing about this area is that, scientists see a similar formation on Mars! Australia's central landscape is well known for it's desert terrain, this area was once covered by sea - about 100 million years ago. As the sea receded, it exposed the pyrite minerals below the water. These minerals saw what is technically termed as 'acidic weathering' and sulfuric acid was released during the process. The weathered surface cracked and silica rich sludge ('gel') entered the veins in the rocks. When the secondary minerals became the next set of materials to be weathered, they covered the silica gel and this, gave the gel a chance to solidify. Scientists believe that the solidified material is what we now know as opal. The entire theory was put forward by a team of Australian scientists, they backed their findings with a research project that took 3 decades to complete.
It is generally agreed that the type of acidic weathering that occurred in the GAB area of Australia, is not seen in any other part of our planet. Geologists refer to a 2008 report finding related to the planet Mars where, it is stated that similar weathering conditions were observed. The general color of Mars and the GAB are also similar. Interestingly, the NASA Mars Orbiter released spectroscopic observations that could be showing opal on the red planet. Gemologists might refer to that opal as 'potch' opal, a term used to describe opal that has a very low quality. Though a distant dream for now, the possibility of selling opals from Mars would indeed stir up tremendous demand for the stone!
For now, gem traders keep sourcing opals from well known sources like Australia, Ethiopia and even Mexico. You can presume (for the next several centuries) that all the gorgeous opal rings you come across, have opals from our very own planet - nothing extraterrestrial!
Gem Enthusiasts: Here is some general information regarding opals. Australia is referred to as the 'Opal Country', there was a time when more than 90% of gem quality opals were mined in that country. While the land of the kangaroos still offers some fine opal gems, other sources are now being tapped. Ethiopian opals have drawn great interest, their durability is always a highly debated issue but, the market has come to accept the more reasonably priced gem. Opal is a birthstone for the month of October along with tourmaline (pink). A fine orange to reddish-orange opal is mined from the volcanic terrain of Mexico - the gem being referred to as 'fire opal'. This gem is valued for it's color and transparency, it does not exhibit the fancy 'play of color' that the legendary opal has become famous for. An affordable pastel pink opal, also with no play of color and flashes, is currently being mined in Peru.