Density, refractivity, and composition relations of some natural glasses

Abstract

Whilst some atention has in the past been devoted to the question of the properties of natural glasses, very little has been done to indicate the interrelations of the properties determined. In the case of tile natural volcanic glasses, this is unfortullately only too evident from a study of the standard text-books. A determination of such properties as density, refractivity, ttud chemical composition, and the interrelations of these for particular glasses, is rarely to be found in the literature. The chief contribution to this subject is due to Stark, who has examined the refringence of a large number of volcanic glasses. Unfortunately, there is no record of the density of these rocks, and the interrelation of these remained unknown.