Gray stones with short small dark shiny lines all over it. Found it on the beaches of Newport Rhode Island.
Given the lighter colored fine grained matrix material with the dark crystals I would suggest that this rock is extrusive with phenocrysts of hornblende (a dark version of an Amphibole). Without addition information about the matrix material or the phenocrysts I would class this rock as a Andesitic hornblende porphyry. See the following site for more information on Andesite (the matrix material) Description of Andesite.