Method for Ultra-Accurate Oxygen Determination for Rare Reference Samples

Abstract

Lunar rocks are deficient in oxygen. In order that a meaningful analysis of oxygen could be performed on lunar, meteoritic, and terrestrial rocks a high degree of accuracy is needed. Because of the rarity of such samples the method selected has to be nondestructive. A highly accurate fast-neutron activation method that permits nondestructive analysis of lunar, meteoritic, and terrestrial rocks is described. It consists of a dual cross-transfer system that corrects for all electronic drifts and surges as well as for neutron beam fluctuation. This method uses chemically different reference samples: silica, aluminum oxide, ferric oxide, calcium carbonate, and their carefully prepared mixtures of which infrared spectra are first taken to ascertain complete absence of water and hydroxyl groups. Accurate oxygen values are reported for six U.S. Bureau of Standards standard reference materials: opal glass, bauxite, Na-feldspar, argillaceous limestone, dolomitic limestone, and the phosphate rock; the U.S. Geological Survey biotite LP-6; and the Smithsonian Institution “AUende meteorite.”