Dependence of red thermoluminescence on Eu-anomaly in natural quartzes

Abstract

The causes of red colour thermoluminescence (RTL) from natural quartzes have been sought in some impurity elements. Some kinds of impurities in 31 varieties of natural quartz extracts, determined by a neutron activation analysis, have been examined with respect to a meaningful correlation of the RTL to the total detectable TL strength. Generally, the higher impurity contents were found in quartzes of volcanic origin, which always emit purely RTL colour, whereas the lower impurities were usually detected in the hydrothermal quartzes, which emit purely blue TL (BTL) in all absorbed doses. Among the impurities, the middle part of the REE (rare earth elements), involving Eu and Sm, particularly offered considerable correlation with RTL emission with the exception of the pegmatite quartzes. It was found from the chondrite-normalized REE patterns that the positive Eu anomaly or flattened Eu distribution brough relatively higher RTL proportions, while the negative Eu anomaly always showed extremely weak RTL intensity. Thus, it was concluded that the quantity of Eu 3+ state, formed from the oxidizable surrounding or high oxygen fugacity relative to Cl chondrite formation, should be remarkably related to the RTL intensity in natural quartzes.