Porphyrische

Porphyrische, or porphyritic, texture is a term used in petrology to describe igneous rocks that show conspicuous larger crystals, called phenocrysts, set in a finer-grained groundmass. The phenocrysts are typically feldspar, quartz, or pyroxene, though other minerals can be present; the groundmass may be aphanitic, microcrystalline, or glassy. The two-scale texture records a two-stage cooling history: crystals grow slowly within the magma at depth, and the remaining melt then cools rapidly as magma rises or is erupted, producing the fine matrix.

Porphyrische textures occur in both intrusive and extrusive rocks. Porphyritic felsic rocks such as rhyolite and granite often display large quartz or feldspar phenocrysts, whereas porphyritic mafic rocks like andesite or basalt contain larger ferromagnesian crystals. The rock type is commonly described as porphyritic granite, porphyritic andesite, or porphyritic rhyolite. The term porphyry refers more broadly to rocks with a coarse-grained phenocryst component within a fine-grained matrix and is also used for certain hydrothermal ore-bearing rocks associated with particular magmatic settings.

In field and laboratory descriptions, the porphyritic texture helps infer crystallization history and magma evolution, aiding classification and interpretation of tectonic and volcanic environments. The term has historical ties to porphyry stones prized in ancient times; in geology it has become a standard descriptor for the two-tier crystal size pattern.