Isotopic and Elemental Composition of Boron in Meteorites, Tektites and Terrestrial Materials

Abstract

<p>The absolute B¹¹/B¹⁰ ratios of meteorites, tektites and terrestrial materials have been determined mass spectrometrically with a precision of 0.17 per cent (two standard errors) for one complete analysis, an accuracy of 0.05 per cent and a reproducibility of the mean of 0.08 per cent (half range).</p> <p>Separation of boron was by cyclic pyrohydrolysis and the quantity determined by curcumin colorimetry with a precision of 9 per cent (two standard deviations), an accuracy (relative to isotope dilution) of 1 per cent and a reproducibility of 5 per cent.</p> <p>The results indicate that there are no differences between the average terrestrial and meteoritic ratios. The slightly high value for Bruderheim (M) is probably due to latter-stage cosmic irradiation. Absorption of marine boron by certain clays produces a 4.8 per cent enrichment of B¹¹ in sea water. Tektites appear to have a sedimentary rather than a chondritic or igneous origin.</p> <p>Mean values of B¹¹/B¹⁰ ratios and boron content for meteorites and the planets are estimated.</p>