by Peter Daley
A pair of imported earrings from the USA, that were to be given as a gift to a friend, where tested with a Geiger counter. It was found that some of the gems embedded in this earring design were radioactive. From the front side, and with the earrings next to each other, they tested 0.90 uSv/hr.
Originally thought the radioactivity was coming from the blue Topaz looking centre stones in this design, because there have been reports of radioactive Topaz being detected in jewelry.After removing these blue stones, and retesting the earrings, the light yellowy green stones positioned around these blue stones, were found to be the main source of the radioactivity. Here are the scintillator and Geiger test charts results for the earrings test. These earrings were purchased as a gift for a friend, from the USA. The main isotopes detected were Thorium Th-234 and Uranium U-235.
The Thorium Th-234 is from Uranium U-238 decay. U-238 puts out hardly any gamma, but the Thorium Th-234 puts out enough for the scintillator equipment to detect it. The presence of Thorium indicates the presence of Uranium U-238, as Thorium Th-234 is a decay daughter of Uranium U-238.
Scintillator test Chart of earrings,
(Click to see larger image)
This explains why there was so much beta detection with the Geiger test. Couldn’t work out why at first. Thorium Th-234 puts out a lot of beta, and a small amount of gamma radiation.
Geiger Counter test chart using a Russian SBT-10 pancake tube.
(Click to see larger image)
Thorium Th-234 info
The small yellowy/green stones on the earrings are Uranium glass made from purified Uranium ore, because there are no decay daughters of Lead Pb-214 or Bismuth Bi-214 isotopes present. It would appear that someone is supplying Uranium glass stones to the jewelry industry.
Most of the radiation is beta radiation with a small gamma component. This is manly from the Thorium 234 decay. Most of the beta radiation body exposure is blocked by the glass stone metal mountings, in this particular earring jewelry design.
Using the Geiger Counter with the SBT-10 tube I detected approximately an extra 0.06 uSv/hr, above background from the rear of the earrings, as opposed to 0.90 uSv/hr from the front.
The Alpha output by Uranium U-238 and U-235 isotopes would be locked into the glass.
Do these earrings pose a health hazard? Probably not in this design, as the wearer is protected from most of the radiation by the metal mountings during use. A resent commenter pointed out that when beta radiation hits metal it can produce bremsstrahlung secondary radiation. This also maybe a potential hazard that needs further investigation.
Do the stones themselves pose a health hazard? Maybe in these, or some other unforeseen circumstances.
Listed in order of possible risk
A. At a manufacturer site or jewelry store, where these stones could be stored in bulk. Being exposed to the dust from cutting or polishing this type of glass, in these environments, could pose the greatest health risk.
B. People spending long hours close up to the jewelry during assembly.
C. A person who had collected a lot of this type of jewelry, and stored it close to where they sleep.
D. Different types of jewelry design using these stones, could be potentially hazardous in these circumstances
1. The piece used larger stones, or more stones.
2. Thinner metal mountings were used.
3. If a piece was worn close to the body. The more proximity and surface area touching the body, means more radiation exposure.
It is suggested that those of you with Geiger Counters check everything that comes into your house.
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