Question: is porphyritic intrusive or extrusive?
Answer: Porphyritic rocks may be aphanites or extrusive rock, with large crystals or phenocrysts floating in a fine-grained groundmass of non-visible crystals, as in a porphyritic basalt, or phanerites or intrusive rock, with individual crystals of the groundmass easily distinguished with the eye, but one group of crystals ...