phenocrysts
/ˈfiːnəkrɪsts/
noun
- Large, visible crystals in a finer-grained igneous rock.
- Under the microscope, the phenocrysts stood out against the dark groundmass.
- The phenocrysts in the lava flow were easily spotted with the naked eye.
- Collectors prize rocks with well-formed phenocrysts for their beauty and scientific value.