Trace elements in precious and common opals using neutron activation analysis

Neutron activation analysis (NAA) was used to determine the concentration of trace elements in 44 precious and 52 common opals sampled from a number of recognised fields within Australia. The purpose of this study was to determine if precious and common opals of the same colour and location have the same or a different trace element profile. Similar numbers of black, white and grey samples were studied in each case. In most cases common opals had a significantly higher concentrationof certain trace elements when compared with precious opals.