Scientists have discovered a completely new type of opal formed by common seaweed which harnesses natural technology by self-assembling a nanostructure of oil droplets to control how light reflects from its cells to display a shimmering array of colours that until now, has only been seen in the gem stone. Opal is formed from a solution of silicon dioxide and water.
As water runs down through the earth, it picks up silica from sandstone, and carries this silica-rich solution into cracks and voids, caused by natural faults or decomposing fossils. As the water evaporates, it leaves behind a silica deposit. This cycle repeats over very long periods of time, and eventually opal is formed. The chemical conditions responsible for producing opal are still being researched, however some maintain that there must be acidic conditions at some stage during the process to form silica spheres, possibly created by microbes. While volcanic-hosted and other types of precious opal are found in Australia, virtually all economic production comes from sediment-hosted deposits associated with the Great Australian Basin. Australia has three major varieties of natural sediment-hosted precious opal - black opals from Lightning Ridge in New South Wales, white opals from South Australia, and Queensland boulder and matrix opal.
By: Swati Kaushal