Westwood Felsite?

Some time ago the local authority on arrowheads, Shirley Blanke, told me that one source for the black rhyolite ("felsite") in Concord arrowheads was Westwood. The Rt 128 Median in Deadham is adjacent to Westwood and I saw rocks like this in what seemed to be highway construction debris:Could this be the Westwood felsite?