Submicroscopic spherules and color of tektites

Magnetic susceptibility measurements of 18 tektites from various strewn fields have been made as a function of temperature from 77°K to room temperature. A relatively large temperature-independent component of the magnetic susceptibility was observed in all cases, and an analysis of the data shows that this component is the result of submicroscopic iron spherules in the tektites. An analysis of the color of tektites in terms of the magnetic measurements and also of the optical absorption spectra suggests that the basic color of all tektites is green or greenish-blue, and that the brown to black coloration in some tektites is due to finely dispersed Fe₂O₃ and/or many metallic spherules, both probably of colloidal size.