Abstract
One hundred and twenty-three dust samples from a variety of sampling instruments were analyzed chemically and by a phase contrast dispersion staining method. Some 40 of these were also analyzed by x-ray diffraction. A high degree of correlation exists among the three methods of analysis for quartz except in the case of samples having a large percentage of the quartz content contained in the small particle size range. The x-ray diffraction method was found to yield values higher than the hot phosphoric acid method for samples having small average particle diameters. The microscopic technique is recommended, particularly for field applications.