Mapping REE distribution in scheelite using luminescence

In situ laser ablation high resolution ICP-MS analyses of scheelite from hy drothermal veins at the Archaean Mt. Charlotte gold deposit (Western Austra lia) show inhomogeneous REE distribution at small scale (<100 mu m). In a l imited number of samples, variations of the cathodoluminescence (CL) colour s from blue to yellow are linked to the REE content of scheelite, and revea l oscillatory zoning of the REE with zone widths between 1 mu m and 100 mu m. However, CL failed to reveal the zoning in most inhomogeneous scheelite samples. A nuclear microprobe has been used to characterize the distributio n of REE in these samples. No reasonable map for the distribution of REE co uld be obtained by particle induced X-ray emission, because of interference s with W-L lines. However, monochromatic ionoluminescence (IL) maps collect ed at the wavelength of the main REE3+ luminescence peaks revealed oscillat ory zoning. Therefore, IL is a powerful tool for mapping the distribution o f REE in natural scheelite. Monochromatic IL maps allow us to determine the nature of the inhomogeneous distribution of REE in scheelite, fundamental information for using the REE in this mineral as a marker for the chemistry of ore-forming fluids, and for interpreting Sm-Nd isotopic data.