The Traprain Law Phonolite

Abstract

Are-examination of the trachytoid phonolite of Traprain Law was undertaken on the suggestion of Mr. E. B. Bailey, in order to determine the characteristics and mode of occurrence of the nepheline contained in it. The slides examined were those of the Geological Survey collection and nine new ones specially cut from material recently obtained. During the course of the examination sodalite and olivine were detected in the rock. These minerals have not been mentioned in previous accounts of the petrography of Traprain Law, and sodalite seems to have been described in only one other rock from the British Isles (14).