Identification of Igneous Rock

You have identified either porhorytic rhyolite or porhoritic granite.
In order to ditinguish between the two take a closer look at the matrix. If the porphorytic texture can be descibed as large crystals in a phaneritic matrix then you have identified porphorytic Granite. If, on the other hand, the porphorytic texture can be descibed as large crystals in an aphanitic matrix you have identified porphorytic rhyolite.