The rapid methods previously used by the U.S. Geological Survey to determine the major constituents of rocks have been modified to introduce atomic absorption spectrometry (AAS) where applicable. Two procedures are available for determining 10 constituents: one, from a single solution prepared by a nitric-acid dissolution of a lithium metaborate-lithium tetraborate fusion, and the other, a two-solution method in which one portion of sample is dissolved in an HF-H2SO4,-HNO3 mixture and another portion is fused with NaOH. In both techniques, SiO2, Al2O3, Fe2O3, TiO2, P2O5, and MnO are determined spectrophotometrically, and CaO, MgO, Na2O, and K2O are determined by AAS. Separate portions of samples are used for the following determinations: FeO by titration with K2Cr2O7 after decomposition with HF and H2SO4; total H2O by its weight when evolved on heating a mixture of sample plus flux; H2O by loss of weight at 110° overnight; CO2 by its volume upon evolution with acid; fluorine by a new indirect measurement of SiO2 evolved with fluorine on heating; and. sulfur by a new procedure based on a turbidimetric measurement of BaSO4, after an aqua regia attack. Several mechanical aids and automated devices are used for the analyses.
|Publication Subtype||USGS Numbered Series|
|Title||Rapid analysis of silicate, carbonate, and phosphate rocks: Revised edition|
|Publisher||U.S. Government Printing Office|
|Description||v, 76 p.|
|Google Analytic Metrics||Metrics page|