斑岩，旧称玢岩，是具有斑状结构的火成岩，比较坚固，可用于做建筑材料。斑晶一般由碱性长石或石英组成，基质为细粒或隐晶（玻璃体）。

斑岩一部分属于火成岩中的喷出岩，但一般属于火成岩中的浅成岩。喷出岩是火山岩浆喷出后冷凝形成的，由于喷出后冷却很快，形成许多细粒；浅成岩是火山岩浆侵入地壳浅层（一般为1.5-3千米）冷凝形成的，有许多结晶斑粒：

喷出岩

浅成岩

Porphyry is a textural term for an igneous rock consisting of large-grained crystals such as feldspar or quartz dispersed in a fine-grained feldspathic matrix or groundmass. The larger crystals are called phenocrysts. In its non-geologic, traditional use, the term porphyry refers to the purple-red form of this stone, valued for its appearance.