The electron microprobe technique allows for nondestructive analyses of smallest parts of materials (in micrometer range) with high precision. Materials that can be analyzed are embedded and polished mineral grains (also gemstones), glass particles as well as rocks. Except for H, He, and Li all elements of the periodic table until including U can be detected and quantified. The detection limits are usually between 5 and 800 µg/g, depending on the comparability of the concentration of the …