SURFACE ALTERATION AND PHYSICAL-PROPERTIES OF GLASS FROM THE CRETACEOUS-TERTIARY BOUNDARY

The scalloped surface feature on Cretaceous-Tertiary boundary glass is often explained as being due to terrestrial aqueous leaching. Leachin g of man-made glass results in a reduction in density of the glass. Al so, Fe, because of its relative insolubility, is concentrated by the l eaching process. Thus, the Haitian glass specimens which have been hea vily altered should have a thin rim of less dense glass in which the F e is concentrated compared to the core glass. The higher Fe concentrat ion in the rim glass should cause it to have an enhanced Curie constan t and a lower density compared to the unaltered glass. The magnetic Cu rie constant, density, and scanning electron microscopic studies were made on altered specimens of Haitian glass and also on specimens showi ng a minimum of alteration. The results show that the less altered sam ples have the highest density and the lowest Curie constant. The data substantiate the terrestrial hypothesis.