Time-resolved spectral mapping and novel LED-based luminescence imaging in analysis of natural REE-bearing minerals

Time-resolved laser spectroscopy techniques (laser-induced breakdown spectroscopy LIBS, Raman and laser-induced luminescence) and LED-based neodymium luminescence imaging method were used in analysis of natural apatite-bearing carbonatite rock samples. The spectral data from the three complementary time-resolved spectroscopy measurements was constructed to distribution maps, which illustrate the spatial elemental and mineralogical composition of the samples. The results yield also comprehensive insight into the grain size and distribution of mineralogical features. Here, the focus was on identification of rare earth element (REE) rich locations, in which these laser spectroscopy methods exhibited excellent performance. Also, a novel LED-excited luminescence imaging approach was developed for direct visualization of neodymium occurrence at a macroscopic scale with results that were consistent with those obtained from time-resolved spectroscopy. This rapid and cost-effective innovation could also easily be designed into field conditions. Our findings demonstrate that time-resolved spectral mapping and LED-based imaging offer a comprehensive view of natural REE-bearing rock samples. Since the REEs are chemically similar, these methods can be readily extended to a wide range of minerals and rock types, enabling rapid analysis of diverse geological materials.