Bugs make quick opals, according to report in Quarterly Notes, Geological Survey of NSW (Australia) June 2011. German and Australian scientists have found fossil microbes in opal specimens from Lightning Ridge Australia. The fossils have been identified as aerobic (oxygen dependent) bacteria actinomycetes (Nocardia, Streptomyces, Micromonospora) and myxobacteria). The organisms normally live in soils rich in organic matter at temperatures less than 35 degrees Celsius and at near-neutral pH, i.e. not acid or alkaline. These microbes produce various organic acids which act on clay minerals to produce silica hydrogel, which is what opal is made of. The researchers concluded: “The kind of environment required by the microbes for life indicates the conditions under which opal was produced. This enables the determination of a new timetable for opal formation involving weeks to a few months and not the hundreds of thousands of years envisaged by the conventional weathering model”.

Editorial Comment: We are not surprised by this new evidence for rapid opal formation. Australian Farmers have regularly reported opalisation in fence posts and other man-made artefacts buried in the soil. One Australian researcher Len Cram, has studied opal formation since the 1950s and has artificially grown opals that are so similar to natural opal they fool experienced miners. His process takes only a few weeks. Although Len is acknowledged as a world expert on making opal, the implications of his research on rapid formation of opals have largely been ignored. His work, and that of the new study reported above, remind us that you don’t need time to make rocks or minerals – you need the right process. When the conditions are right the processes can occur very rapidly. If not, rock and mineral formation is a bust.

Evidence News 2 November 2011