Porphyritic texture

An igneous texture in which larger crystals, called phenocrysts, are embedded in a finer-grained groundmass. It records contrasting conditions during crystal growth and cooling.

Phenocryst: A conspicuously large crystal embedded in a finer-grained igneous groundmass. Phenocrysts are the large crystals that define this texture.
Igneous rock: Rock formed when magma or lava cools and solidifies. Porphyritic texture is a fabric found in igneous rocks.
Porphyry (geology): An igneous rock characterized by conspicuous crystals set in a finer-grained groundmass. Porphyry is a rock description commonly associated with this texture.
Magma mixing: The blending of magmas with different compositions or temperatures within a volcanic system. Mixing can change temperature and composition, prompting renewed crystal growth.
Porphyritic granite: Granite containing conspicuously larger crystals, often feldspar, in a finer crystalline matrix. It demonstrates the texture in a coarse-grained intrusive rock.
Groundmass: The finer-grained material surrounding larger crystals in a porphyritic igneous rock. Its fine grain contrasts with the phenocrysts and completes the texture.
Texture (geology): The size, shape, and arrangement of mineral grains in a rock. Porphyritic texture is one specific arrangement of igneous crystals.
Porphyritic basalt: Basalt containing larger crystals, commonly of plagioclase or pyroxene, in a finer groundmass. It shows how porphyritic texture appears in a common volcanic rock.
Magma recharge: The injection of new magma into an existing magma reservoir. Recharge may disrupt earlier crystallization and produce a new fine-grained matrix.
Porphyritic rhyolite: Rhyolite with larger crystals set in a fine-grained or glassy groundmass. It illustrates the texture in a silica-rich volcanic rock.

Linked from 9 pages