United States Geological Survey Report 215

Abstract

Abstract: The scope of the semiquantitative spectrographic method for the analysis of minerals, rocks, and ores previously described as determining 55 elements, has now been increased to 68 elements which can be estimated in one exposure of a l0-mg sample. Fluorine, the 69th element, requires a separate exposure for some materials. The method has been used to complete about 185,000 determinations in the past two years. Listed in this report are 336 chemical check analyses that indicate approximately 8 percent disagreements in the magnitude of one 10 percent bracket. No chemical and spectrographic results differ by a factor of more than 10