Use of the Soft X-Ray Spectrograph and the Electron-Probe Microanalyzer for Determination of Elements Carbon through Iron in Minerals and Rocks
The major elements in common rocks are of low atomic number, but analyses of high precision are possible by soft X-ray spectrography if several grams of rock sample are available. The electron-probe microanalyzer is shown to complement this established method by permitting analyses of particles as small as 1 μ in diameter. This paper describes applications of these methods to the analysis of the major and minor elements of silicate, carbonate, and phosphate minerals and rocks.
Elements of particular interest are as follows: carbon in particles enclosed in carbonate rocks; oxygen, as the major constituent of the specimens; phosphorus in phosphatic nodules and apatites; manganese and iron, as colorations in fossil shells; and the group oxygen, sodium, magnesium, aluminum, silicon, potassium, calcium, and iron as complex segregations and zonations within single crystals of several mineral phases.
If the bulk composition of a rock is known, and also the chemistry of the constituent minerals, it is possible to compute quantitative mineralogic analyses of high precision. Thus, the combined use of soft X-ray spectrography and electron-probe microanalysis can provide quantitative chemical and mineralogical information on the earth’s crust on all scales from thousands of square miles (by means of appropriate sampling) down to the scale of 1 μ.
KeywordsTransmitted Light Sample Current Probe Optic Bulk Analysis Beam Damage
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- 4.E. E. Welday, A. K. Baird, D. B. McIntyre, and K. W. Madlem, “Silicate Sample Preparation for Light Element Analyses by X-ray Spectrography,”Am. Mineralogist 49: 809, 1964.Google Scholar
- 5.D. B. McIntyre, “Fortran II Programs for X-ray Fluorescence,” Technical Report 13, Department of Geology, Pomona College, 1964.Google Scholar
- 9.A. K. Baird, D. B. McIntyre, and E. E. Welday, “Granitic Rocks of the San Bernardino Mountains, California: Chemical Composition and Variability Within 2000 Square Miles,”Geol. Soc. Am. Spec. Papers 82: 6, 1965.Google Scholar
- 10.A. K. Baird, D. B. McIntyre, E. E. Welday, and D. M. Morton, “A Test of Chemical Variability and Field Sampling Methods, Lakeview Mountain Tonalite, Southern California Batholith,”Calif. Div. Mines and Geol., Shorter Cont.,in press.Google Scholar
- 11.D. A. Copeland, “A Simple Device for Trimming Thin Sections,” Am. Mineralogist 50: 1128, 1965.Google Scholar
- 12.A. Johannsen,A Descriptive Petrography of the Igneous Rocks, Vol. 1, University of Chicago Press, Chicago, 1931, p. 89.Google Scholar
- 13.D. B. McIntyre, “Fortran II Program for Norm and Von Wolff Computations,” Technical Report 14, Department of Geology, Pomona College.Google Scholar
- 14.B. L. Henke, “Application of Multilayer Analyzers to 15–150 A Fluorescence Spectroscopy for Chemical and Valence Band Analysis,” this volume, p. 432.Google Scholar