noun

porphyry

POR-fuh-ree/ˈpɔːrfəri/

Igneous rock with large crystals embedded in a fine-grained background.

Large, pale crystals stand out against this porphyry's dark, fine-grained background.

Close-up of one chunky porphyry rock on a plain background. Its broad exposed face shows several large, pale, angular crystals embedded throughout a dark reddish-gray, finely speckled matrix. Rough, jagged outer edges suggest hard stone; emphasize the strong contrast between the large crystals and tiny surrounding grains. No lettering or extra props.

Etymology

The Greek ancestor meant purple stone, naming the color of an ornamental rock. The modern geological name instead identifies its texture—large crystals embedded in a finer base—regardless of color.

In context

Professor Travis0:01

here i have a basalt porphyry and this one's a good basalt porphyry but it's kind of hard to see but you can see some of these phenocrysts in here

Igneous Lab: Basalt Porphyry

More examples

The geologist points out the larger crystals in a piece of porphyry.
The museum's polished porphyry columns contain pale crystals in reddish stone.
Despite its name, porphyry does not have to be purple.

Forms

porphyry · porphyries

porphyritic adjective — Having large crystals in a fine-grained background.

Similar words

porphyritic rock: Emphasizes the contrasting crystal sizes rather than a rock name.