ELEMENTAL COMPOSITION AND NUCLEAR PARAMETERS OF SOME COMMON SEDIMENTARY MINERALS

Major and trace element chemistry has been used to investigate critical characteristics of 89 specimens of 15 minerals that are commonly found in sedimentary rocks. For kaolinites, Na+, Mg2+ and Ca2+ are exchangeable cations while other elements are essentially non-exchangeable. The compositional variability of most minerals is seen to be quite low (even for clay minerals) which bodes well for resolving the mineralogy of formations from down-hole elemental data. Nuclear parameters such as the photoelectric absorption cross section, natural gamma-ray activity, thermal neutron absorption cross section and neutron porosities calculated from chemical analyses of minerals often exceed values calculated using simple chemical formulae.