A field method of spectrographic analysis for use in geochemical exploration work

The method to be described is a modification of an earlier method of semiquantitative procedure. Through its use 34 elements can be determined simultaneously in one sample, which may be a rock, soil, mineral, or an ore. For many of these elements concentration ranges from one to ten thousand parts per million (0.0001 to 1 percent) or more can be investigated (see table 1). The modification in the method is the addition of 20mg of a CaCO₃-graphite mixture (1:5) on top of the sample-graphite powder. This addition gives a smoother burning arc and minimizes sample loss during arcing, so that the former variability of results is also minimized. The improved procedure has been tested in a truck-mounted spectrographic laboratory constructed and used by the U. S. Geological Survey in geochemical exploration.