Abstract
Hokutolite consists of barite (BaSO <sub>4</sub> ) and anglesite (PbSO <sub>4</sub> ), and contains significant amounts of radium isotopes as a radioactive mineral. Photon activation and gamma-ray spectrometry were employed to determine Ba, Pb and <sup>226</sup> Ra contents in hokutolite samples and to investigate the correlation between <sup>226</sup> Ra activity and both Ba and Pb content. <sup>226</sup> Ra activity in 30 hokutolite samples were estimated in the range of 40-65 Bq/g and was positively related to Ba content (r=0.859, p<0.001), but independent of Pb content (r=-0.236, p=0.217). Experimental results implied that <sup>226</sup> Ra preferably precipitated with Ba over Pb. The <sup>226</sup> Ra activity in hokutolite from the Peitou Hot Spring was experimentally estimated based on the Ba/Pb ratio and expressed as <sup>226</sup> Ra (Bq/g)=14.67 (Ba/Pb) <sub>molar</sub> +14.13. © 2008 Elsevier Ltd. All rights reserved.