In this paper is presented a detailed petrographic description of an unusual alkaline vitrophyre dike intruding a mass of breccia on Nubble Island, off Cape Neddick, Maine. The rock possesses strong flow banding, skeletal crystals, several varieties of incipient spherulitic structures, and contains devitrification aggregates typical of modified pitch-stones. Chemical analysis indicates its strong nordmarkitic or sölvsbergitic affinities, suggesting its relationship to the paisanitic and monchiquitic dikes which cut riebeckite granite at nearby York Beach.

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