Final answer:
Porphyritic texture in rocks is characterized by large crystals, known as phenocrysts, and a finer-grained matrix; the terms 'large crystals' and 'small crystals' are appropriate for describing these components.
Step-by-step explanation:
A porphyritic texture in rocks signifies the presence of large crystals, known as phenocrysts, which are embedded within a finer-grained or aphanitic ground mass or matrix. When describing portions of a rock with a porphyritic texture, we could use the terms:
- Large crystals to describe the phenocrysts.
- Small crystals to describe the matrix that surrounds the phenocrysts.
A glassy texture would only be used if the ground mass solidified so quickly it formed glass instead of small crystals. The term metallic is not typically used for porphyritic textures unless a metal-bearing mineral has a phenocryst that possesses a metallic luster.