Several years ago a party of students on a field trip near Peek-skill collected some specimens of thomsonite, and I believe this is a locality from which it has not heretofore been reported. Locally it occurs two miles east of Peekskill and about five hundred feet south of Dalton’s emery quarry, in an area termed pyroxenite by G. S. Rogers,1 in his paper on the “Cortland series and its emery deposits.” He however mentions a mineral occurring in some of his sections of a sodalite syenite, lying near the thomsonite locality, which from its optical properties he thought might be thomsonite, and from its hexagonal outline was believed to be a secondary product from nephelite.

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