A model for converting relative elemental yields from a pulsed neutron spectroscopy log to absolute weight concentrations using the assumption that the sum of all oxides in the rockmatrix is 1. The model is based on the observation that, with few exceptions, sedimentary minerals are oxides, so that the sum of the dry weight percent of all oxides must be 100%. The weight percent of an oxide can be calculated from the dry weight percent of the cation by knowing the chemical formula (for example, SiO_{2} from Si).
The absolute dry weight percent, W, of element i is given by W_{i} = F * Y_{i} / S_{i} where F is the unknown normalization factor, Y_{i} is the measured spectral gamma ray yield and S_{i} is the tool sensitivity to that element, measured in the laboratory. The dry weight percent of the oxide is then O_{i} = F* X_{i} * Y_{i} / S_{i} where X_{i} is the oxide association factor, given by the chemical formula. Since the sum of all O_{i} equals 1, it is possible to calculate F and determine each W_{i} .