Porphyroblast｜斑狀變晶：變質岩裡的大晶體能在整塊岩石仍是固態時後來長大

A porphyroblast is a relatively large crystal that grows during metamorphism within a finer-grained matrix. Such crystals, including garnet porphyroblasts in schist, can grow while the rock remains solid through diffusion and metamorphic reactions rather than crystallizing from a melt.

porphyroblast 和火成岩 phenocryst 外觀上都可能是大晶體包在細基質裡，但成因不同；判斷要結合岩性與變質組織。