Two noted Australian scientists may have developed a method to scientifically prospect for precious Australian opal. Dr. Brian Senior and Professor Lewis Chatterton have spent 20 years developing a technique that uses the low level natural radioactivity, from uranium and thorium, present in opals to “see” into the tunnels and shafts of the opal mines to better pinpoint opal deposits. Hopefully this will give miners a better edge in opal exploration than test drilling, dowsing or “throwing your hat into the air and see where it lands” has traditionally provided the opal miner.
Professor Chatterton from The Australian National University has been quoted as saying: “Australia is home to the largest and most widespread deposits of precious opal and accounts for 95 per cent of the world’s production. Opal deposits are found within deeply weathered sedimentary rocks in the Great Artesian Basin that occupies almost one fifth of the continent’s centre and east. Geologists agree that there are vast areas within the Basin where opal is likely to occur, but until now there was no means of detecting this mineral other than by direct recovery of opal fragments during exploratory drilling. Opal sites tend to be discrete and sporadic, so even drilling within a rich deposit can be fruitless unless there is a direct hit.”
With the advantage of using instruments capable of detecting very low levels of gamma radiation, opal miners may be able to direct their tunneling machines or (more traditional) explosive efforts toward the source of the radiation and hopefully larger deposits of this elusive and bewitching gemstone.
Not to worry about opal radiation though. I have worked in the medical imaging field for 29 years with all forms of medical radiation devices and possess my own multi-purpose radiation survey meter (Geiger counter). I have checked all of the opals in my possession and have been unable to detect anything other than background radiation. So, I would assume, we are talking about VERY low-level specific energy spectrums from whatever thorium or uranium isotopes are present in opals. Interesting though this may be, I would guess very sensitive scintillation detection equipment may be expensive and bulky…but only time will tell.