GRANOPHYRE

fine-grained igneous rock that is characterized by a porphyritic texture, having large crystals (phenocrysts) that rest in a nonglassy, finely crystalline matrix (groundmass). Granophyre is similar to granite, except for its fine texture and smaller grain size; those granophyres that have quartz and alkali feldspar phenocrysts in a groundmass of quartz, alkali feldspar, and mafic (dark-coloured) minerals resemble rhyolite, while others consist of micropegmatite (q.v.).