noun
- a large crystal embedded in a finer-grained igneous rock
Usage: geology
Examples
- The granite contained large feldspar phenocrysts visible to the naked eye.
- Quartz phenocrysts gave the volcanic rock a distinctive speckled appearance.
- The geologist identified olivine phenocrysts in the basalt sample.
- Phenocrysts form when magma cools slowly before eruption.
- The porphyry texture was created by phenocrysts surrounded by fine-grained matrix.
- Large hornblende phenocrysts were scattered throughout the andesite.