(via ICA Early Warning Flash, No.23, November 1989) Kurt Nassau writes:
A New York gemstone merchant accidentally placed a parcel of spinel triplets near his Geiger counter and was surprised when radioactivity was detected. Some of the stones involved were examined by me. They are yellow green, apparently intended to imitate peridot, and are said to be manufactured in Europe. Analysis shows that they consist of two layers of colorless spinel cemented together with a green lead and uranium-containing glass. The uranium provides both the color and the radioactivity. A single stone counts only just double the background on a small ‘monitor 4’ Geiger counter; accordingly the amount of radiation produced from an individual stone is not easy to detect and probably harmless. Nevertheless, significant activity is given off by a parcel containing many such stones. Gemologists and dealers should be aware of this situation.
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